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Reptiles: General Characteristics, Classification and Examples

Reptiles belong to the class Reptilia under subphylum Vertebrata of phylum Chordata. The representatives of modern reptiles include turtles and tortoises, crocodiles and aligators, snakes, lizards, amphisbaenians and,  tuataras.  The science which deals with study of modern amphibians and reptiles is collectively called herpetology.

The body size ranges from 17 mm (0.7 inches) to   6 m (19.7 ft) in length. In this case, a tiny gecko (Sphaerodactylus ariasae) can grow up to 17 mm (0.7 in) in length while the saltwater crocodile (Crocodylus porosus) can reach up to 6 m (19.7 ft) in length with over 1,000 kg in weight.

Generally, reptiles are the cold-blooded vertebrate animals which are unable to maintain a definite body temperature. Usually, the body temperature varies with the outside temperature. They have a low metabolic rate and therefore, produce less heat than a bird or mammal. They have evolved from amphibians and in turn, gave rise to the birds and mammals. As a group the reptiles can be separated from the amphibians by their dry cornified scaly skin and from the birds by the absence of feathers and from the mammals by the absence of hairs or furs.

Reptiles are the first group among the vertebrates adapted for life in dry places on land. They have dry horny skin and scales which resist loss of moisture from the body and facilitate living on rough surfaces. Most reptile species live in tropical and subtropical regions and their numbers decline towards the poles and high attitudes. They occupy a wide verity of habitats; some live in the tropics, some in swamps, rivers, estuaries or along the seacoasts.

The reptiles originated during the Carboniferous period, some 300 to 260 MYA and flourished during the Permian period. During the Mesozoic Era, popularly known as the Age of Reptiles (Triassic to upper Cretaceous), they were the dominant vertebrates. During this time, the dinosaurs flourished and some of them far exceeding elephants in length and weight and were greatly diversified as to structure and habits. During Permian, reptiles became numerous as to number of species and began to radiate in both structure and mode of life. By the end of Triassic period, virtually all the major groups of reptiles had appeared and during the Jurassic and Cretaceous these attained a climax as to number of species and individuals and also in diversity of form and manner of life. Then the end of the Cretaceous, the reptiles started to decline and most of the species disappeared and only 4 of the 16 orders survived.

General Characteristics of Reptiles

  1. They are the cold-blooded vertebrate animals.
  2. They have dry horny skin, usually with scales or scutes.
  3. Reptiles have completely ossified skeleton.
  4. The skull contains one occipital condyle.
  5. The heart is imperfectly four-chambered.
  6. Twelve pairs of cranial nerves are present.
  7. Reptiles perform respiration by lungs.
  8. They have two pairs of limbs, each with five toes ending in horny claws and suited to running, crawling, or climbing (exception snake and some lizards).
  9. Limbs are paddle-like in marine turtles and reduced in some lizards.
  10. Fertilization is internal, usually occurs by copulatory organs.
  11. Most reptiles are oviparous but some species are viviparous.
  12. They usually lay eggs but retained in female body for development by some lizards and snakes.
  13. Eggs are fairly large with much yolk, in leathery or limy shells.
  14. The new-born resemble adults with no metamorphosis.
  15. Unlike amphibians, they never depend on aquatic medium for growth and development.

The living or modern reptiles are mostly small and inconspicuous. Majority of them appeared during the Tertiary Period, some 70 MYA. At present the number of living reptile species is over 8700 included under the following four orders:

  • Order-1: Testudines-turtles, tortoises and terrapins;
  • Order-2: Rhynchocephalia-tuatara;
  • Order-3: Squamata-lizards and snakes and
  • Order-4: Crocodilia- crocodiles, gavials caimans, and alligators.

Order-1: Testudines

  1. The order Tesudines contains around 300 extant species in 97 genera.
  2. The representatives of order Testudines are turtles, tortoises and terrapins, collectively called Testudines.
  3. They do not contain teeth but each jaw is covered with a horny sheath, form a beak which is sharpened or serrated to cut flesh or plant matters.
  4. They also contain bony shell comprising an upper carapace and a lower plastron, both composed of solid bony plates. In most cases, this bony shell is further covered by a layer of thick horny scales which form the visible part of the shell but some have a softer, leathery, covering.
  5. They have strong limbs to lift their heavy bodies. In this case, the shape of the limb is variable, however, in land dwelling species typically the toes are fused into a solid clump, freshwater species having distinct but webbed, toes and marine species having powerful flippers.
  6. They lay eggs in a nest chamber, but no species displays parental care.

The order Testudines includes the following families:

  • Family-1: Carettochelyidae
  • Family-2: Chelydridae       
  • Family-3: Dermatemydidae
  • Family-4: Emydidae            
  • Family-5: Kinosternidae 
  • Family-6: Platysternidae
  • Family-7: Chelidae
  • Family-8: Pelomedusidae
  • Family-9: Podocnemididae
  • Family-10: Testudinidae 
  • Family-11: Geoemydidae
  • Family-12: Trionychidae 
  • Family-13: Chelonidae  
  • Family-14: Dermochelidae

Family-1: Carettochelyidae

  1. The family Carettochelyidae contains only one species (Carettochelys insculpta), commonly known as pig-nosed turtle,   Fly River turtle or shelled turtle.
  2. Its habitat is restricted to northern Australia and southern New Guinea.
  3. It prefers to live in all the larger and smaller flowing rivers, lagoons, and even some brackish waters.
  4. It has pig-like nose with nostrils at the end of a fleshy snout which gives the common name pig-nosed turtle.
  5. The forelimbs are paddle-like having two claws.
  6. It has 70 cm long domed bony carapace under a leathery skin with olive or gray in color.
  7. The plastron is solid with cream color that connects the carapace by a strong bony bridge.
  8. The pig-nosed turtle reaches a length up to 70 cm with over 20 kg in weight.
  9. It is omnivorous and its food consists of wide variety of plants (fruit and leaves of figs) and animals maters such as crustaceans, molluscs and insects, etc.
  10. It reaches a sexual maturity at the age between 16-18 years.
  11. The female lays eggs on sandy river banks during the late dry season.

Examples: Pig-nosed turtle (Carettochelys insculpta)

image of Carettochelys insculpta

Family-2: Chelydridae

  1. The family Chelydridae contains only extant genera (Chelydra and  Macrochelys), commonly called snapping turtles and they are endemic to the Western Hemisphere.
  2. They are large aquatic turtles with a long tail with three rows of tubercles and a hooked beak.
  3. They have a keeled, posteriorly serrated carapace with a reduced, cruciform, hinge less plastron. In this case, each side of the carapace bears 11 marginal scutes.
  4. The scutes of the abdominal region of plastrons are reduced. The carapace and plastron are connected by a narrow bony bridge.
  5. The skull roof of posterior part is deeply emarginated.
  6. The size of the body ranges from 18–80 cm (7.1–31.5 inches) in length with up to 113 kg in weight. In this case, the male is larger than the female.
  7. They reproduce during the spring or early summer and the female lays up to 109 eggs per clutch per year.

Examples: Alligator snapping turtle (Macrochelys temminckii), Common snapping turtle (Chelydra serpentina), etc. 

image of Common-snapping-turtle-(Che

Family-3: Dermatemydidae

  1. The family Dermatemydidae contains only one species, known as Central American river turtle or river turtle (Dermatemys mawii).
  2. It inhabits large river and lakes of Central America.
  3. It is totally aquatic which grows up to 65 cm in length.
  4. The body of the river turtle is olive to gray in color with no keel in a carapace.
  5. It has a small head with a pointy snout.
  6. The carapace is somewhat flat, heavy, and smooth.
  7. The lower shell or plastron is yellow or cream color which connects the upper shell or carapace by the bony bridge.
  8. The feet are webbed.
  9. The female is generally larger than the male. In this case, the upper surface of the head of male bears a large yellowish gold patch while the females have gray patch on the top of the head.
  10. It can grow up to 66 cm (26 inches) in length (carapace length) with 22 kg in weight.
  11. They are nocturnal and they eat mostly plants.  They also prefer to eat figs and other fruits, insects, fish or mollusks.
  12. During the breeding period, the female makes a nest on the shore by digging a hole into soil and lays 2-20 brittle shelled eggs.
  13. The eggs hatch within 7-10 months when the rainy season stars up.

Examples: Central American river turtle (Dermatemys mawii)

image of Central-American-river-turt

Family-4: Emydidae     

  1. The members of the family Emydidae have several common names including Blanding’s turtle, chicken turtle, box turtle, spotted turtle,  painted turtle, pond turtle, wood turtle or marsh turtles.
  2. The family contains over 85 living species in 25 genera.
  3. They have small to moderate sized body having depressed, domed, or strongly keeled carapace.
  4. The body size ranges from 5 inches (12 cm) to 24 inches (60 cm) in length or more.
  5. The males are generally smaller than the females
  6. They are carnivorous to strictly herbivorous. The carnivorous species mainly feed on annelids, crustaceans and fish. 
  7. They inhabit wide variety habitats including freshwater rivers, streams, lakes, and ponds, estuaries and coastal waters. Some species are semi-aquatic to fully terrestrial.
  8. During the breeding season (spring), the female lays up to 24 eggs in the holes. The eggs hatch within 2-3 months. The female does not show no care for the eggs and their babies.    

Examples: Pond or water turtles, Red-eared slider (Trachemys scripta elegans)

image of Pond or water turtles, Red-eared slider (Trachemys scripta elegans)

Family-5: Kinosternidae

  1. The family Kinosternidae contains 25 species under four genera.
  2. They are generally small in size which range from 3-15 inches (8-38 cm) in length.
  3. The shell is brown or black with oblong and moderately domed shaped while the head is greatly enlarged with sensory barbels on the chin.
  4. They have dark-olive to black color skin with two prominent yellow lines, of which one runs from the snout to the neck while the other one on both sides of the eye.
  5. They inhabit nearly any freshwater aquatic system. They prefer to live in slow-moving or still waters where vegetation available.
  6. They are primarily carnivorous and their food consists of snails, clams, annelids, crustaceans, insects, amphibians, small fish and sometimes carrion.
  7. The female lays up to 12 eggs in each clutch and eggs need long time to hatch (75 days to a year).

Examples: Mud or musk turtles, Common musk turtle (Sternotherus odoratus), Tabasco mud turtle (Kinosternon acutum), Yellow mud turtle (Kinosternon flavescens), etc.

image of Mud-or-musk-turtles,-Common-mus

Family-6: Platysternidae 

  1. The family Platysternidae contains only one species, known as the bigheaded turtle (Platysternon megacephalum).
  2. It has small to medium-sized body with up to 40 cm in length.
  3. It has huge sized triangle head which is covered by a hard scute.
  4. The upper shell or carapace is quite flat with yellow to dark-brown color. 
  5. The lower shell or plastron is yellow in color which covers most of the underside.
  6. The tail is long and muscular with scaly and the toes are slightly webbed with strong claws.
  7. The member of the family Platysternidae lives in only in small rocky and mountain streams of China, Laos, Myanmar, Thailand, and Vietnam. It prefers to live in fast moving water bodies with a temperature of 12-170C.
  8. The big-headed turtle is carnivorous and feeds on insects, crustaceans, mollusks (snails and clams), and other small invertebrate.
  9. During the breeding season (May to August), the female lays one to four eggs in nest. The eggs need to hatch between 103 and 110 days.

Examples: Big-headed turtle (Platysternon megacephalum)

image of Big-headed-turtle-(Platyste

Family-7: Chelidae

  1. The members of the family Chelidae are commonly called the side-neck turtles or snake-necked turtles.
  2. They are distributed in tropical to temperate regions of Australia and New Guinea, some parts of Indonesia, and South America.
  3. They are primarily aquatic and inhabit freshwater rivers, lakes, streams, seasonal wetlands and ponds but some species live in estuaries and coastal waters.
  4. The forelimbs bear five claws while in hind limbs contain four claws.
  5. The neck is extremely elongate which may exceed that of the carapace.
  6. The carapace is dark and cryptic while the plastron has bright red, pink, orange, and yellow colors.
  7. They are carnivorous and mainly feed on invertebrates, gastropods and fish,
  8. They breed during the spring and summer and they typically build nests.
  9. The female lays up to 28 brittle-shelled eggs per clutch. Eggs need to hatch more than 200 days

Examples: Austro-American sideneck turtles, Common snakeneck turtle (Chelodina longicollis)

image of Common snakeneck turtle (Chelodina longicollis)

Family-8: Pelomedusidae

  1. The members of the family Pelomedusidae are commonly called African side-necked turtles.
  2. They are freshwater turtles, distributed in Africa, South America Madagascar, and the Seychelles Islands.
  3. The family Pelomedusidae contains about 26 species in five genera.
  4. They primarily live in temporary ponds, large rivers, and swamps.
  5. Generally, the carapace is oval in shape with some shade of olive coloration.
  6. The size of the upper shell or carapace ranges from 12 to 107 cm in length.
  7. The members of the family Pelomedusidae prefer to live in the  bottom region of rivers or shallow lakes.
  8. They are carnivorous and mainly feed on insects, crustaceans molluscs, worms, fishes, and amphibians. But some are omnivorous and eat fallen fruits and aquatic vegetation.
  9. They are egg layers and the female lays up to 100 eggs per clutch.

Examples: Afro-American sideneck turtles, African helmeted turtle (Pelomedusa subrufa)

image of African-helmeted-turtle-(Pe

Family-9: Podocnemididae

  1. The members of the family Podocnemididae are commonly called side-necked turtles.
  2. They are native to Madagascar and northern South America.
  3. They are all aquatic and prefer to live in freshwater habitats including permanent slow streaming rivers, flooded forests, lakes and backwaters. But some hatchling and juvenile turtles travel into smaller rivers.
  4. The head is very large and shell is hard, streamlined with brown in color.
  5. The size of the body reaches a length of 17-20 inches (43-50 cm).
  6. The soft pattern of fine black lines is present on the shell of the young turtles which disappear with age.
  7. The members of the family Podocnemididae are primarily herbivorous and mainly feed on fruits, leaves, stems, and grasses. Occasionally, they also take freshwater sponges, crustaceans, insects, mollusks and fish.
  8. During the breeding season, the female comes ashore and build a nest on sandbars and river banks. She lays 10- 25 leathers, textured elongated eggs into the nest. Eggs need to hatch 40–149 days.

Examples: Madagascar big-headed turtle (Erymnochelys madagascariensis)

image of Madagascar-big-headed-turtle

Family-10: Testudinidae 

  1. The representatives of the family Testudinidae are commonly known as Tortoises.
  2. They are strictly terrestrial.
  3. They have high-domed carapaces and frequently with distinct growth rings.
  4. Plastrons are large in size.
  5. They have column-like or elephantine hind limbs.
  6. The infront of forelimbs is covered with thick scales with all the toes are without webs.
  7. In general, they can live up to 150 years.
  8. They are oviparous and can lay up to 20 eggs.
  9. The eggs hatch within 120 days.

Examples: Tortoise, Aldabra giant tortoise (Geochelone gigantea)

image of Tortoise, Aldabra giant tortoise (Geochelone gigantea)

Family-11: Geoemydidae

  1. The family Geoemydidae includes turtles that have oval to oblong and moderately domed or flattened carapaces.
  2. Plastrons are large in size and occasionally hinged.
  3. The skull contains epiterygoid and the internal carotid canal in the pterygoid.
  4. The carapace has 11 pairs of sutured peripherals around its margin and nuchal without costiform processes.
  5. The size of the body varies from about 10 to 80 cm (4 to 30 inches) in length. 
  6. Their neck withdraws vertically.
  7. The carapace bears 24 marginal scutes.
  8. The plastron contains12 scutes with no mesoplastron.
  9. They inhabit wide variety habitats including tropical forests freshwater ecosystems and, coastal marine areas.
  10. Most of them are herbivorous, but some species are omnivorous or carnivorous.

Examples: Asian river, leaf, roofed, Asian box turtles or Malayan box turtle (Cuora amboinensis)

image of Cuora-amboinensis

Family-12: Trionychidae 

  1. The members of the family Trionychidae are commonly known as the soft-shelled turtles.
  2. The head and the neck are completely retractile.
  3. The carapace and plastron are covered by a continuous layer of soft skin with no epidermal scutes.
  4. The side of the hinder portion of carapace is quite flexible.
  5. Limbs are fully webbed with only three claws on each foot.
  6. Forelimbs are semi-paddle shaped.
  7. Soft, elongated and snorkel-like nostrils are present.
  8. Most of the members are predominantly carnivorous but some species eat plant matters. In this case of carnivorous species, food mainly consists of fish, crustaceans, snails, amphibians, aquatic birds and small mammals.

Examples: Softshell turtles/Spiny softshell turtle (Apalone spinifera)

Family-13: Chelonidae

  1. They are the typically large marine turtles with six extant species.
  2. They have a flat streamlined wide and rounded shell.
  3. The forelimbs bear almost paddle-like flippers.
  4. The body size of the sea turtles ranges from 71 to 213 cm. In this case, the Kemp's Ridley is the smallest turtle species with a shell size about 75 cm and 50 kg of weight.
  5. The carapace and plastron are covered by horny epidermal shields.
  6. The neck is incompletely retractile.
  7. The legs are modified to form swimming paddles with scale covering feet.
  8. The digits of forelimbs are much elongated with one or two claws.

Examples: Green sea turtle (Chelonia mydas), Hawksbill sea turtle (Eretmochelys imbricata), Flatback sea turtle (Natator depressus), Olive ridley sea turtle (Lepidochelys olivacea), Kemp's ridley sea turtle (Lepidochelys kempii), Loggerhead sea turtle (Caretta caretta).

image of Green-sea-turtle-(Chelonia-

Family-14: Dermochelidae

  1. This family contains only one extant species, Dermochelys coriacea, found worldwide in oceans.
  2. The size of the body reaches up to 244 cm in length and over 800 kg in weight.
  3. The dorsal bony shell is composed of numerous small different sizes polygonal plates.
  4. The entire body of the turtle is covered with rubber-like skin.
  5. They are oviparous and the female lays eggs six times within a single season.
  6. They are pelagic feeder and feeds almost exclusively on jellyfish.
  7. The carapace consists of seven keels and the head cannot be fully retracted within the shell.

Examples: Leatherback sea turtle (Dermochelys coriacea)

Order-2: Rhynchocephalia

  1. The order Rhynchocephalia includes the only extant rhynchocephalians, the tuataras.
  2. They occur only on small islets off the main islands of New Zealand.
  3. The extant rhynchocephalians flourished around 200 million years ago but all other members became extinct in the late Cretaceous period (60 MYA).
  4. Along their backs have spiny crests which are made from soft, triangular folds of skin.
  5. The size of the tuatara ranges from 12-30 inches in length with weight between 0.5 and 2.5 pounds.
  6. The skin is greenish gray or speckled in colors.
  7. The adult tuataras have beak-like premaxilla which bears a large chisel-shaped tooth.
  8. They reach sexual maturity at the age between 10 and 20 years.
  9. The male mates each year while the female breeds every two to five years.
  10. They are carnivorous and take a wide variety of foods which include beetles, snails, lizards, spiders, and young seabirds.
  11. In wild condition, they can live up to 100 years or more.
  12. The tuatara contains parietal eye, situated on the top of its head and only visible in hatchlings but it becomes covered under scales and pigments after four to six months.
  13. They can tolerate much lower temperatures and the body temperature ranges from 41 to 52 °F whereas the body temperatures of most reptiles have around 68 °F. 
  14. The lower jaw bears a single row of teeth while the upper jaw contains a double row of teeth.

Family-1: Sphenodontidae

  1. The family Sphenodontidae contains only one living member, the tuatara (Sphenodon punctatus) which occurs in New Zealand.
  2. They have roughly iguana-like appearance.
  3. Dorsal spines are present on the neck and head with a thick tail.
  4. They can grow up to 80 cm in length with average weight less than 1 kg.
  5. They are primarily nocturnal carnivorous and they mainly feed on arthropods, beetles, snails, small lizards, amphibians, and juvenile seabirds.
  6. They reach sexual maturity at the age between 10 and 20 years.
  7. They reproduce only once every 3-4 years. In this case, they mate during summer months and lay clutches of 8-15 eggs, next summer deposited in the nests. The hatchlings come out between a year and 16 months later.
  8. At present, they are now highly endangered due to various human activities.

Example: Tuatara (Sphenodon punctatus)

image of Tuatara-(Sphenodon punctatus)

Order-2: Squamata

  1. The members of the order Squamata comprise the largest order of reptiles with over 10,000 species.
  2. They include lizards, snakes and worm lizards (amphisbaenians), collectively called scaled reptiles or squamates.
  3. They have horny epidermal scales or shields.
  4. Movable quadrate bone is present with no vomerine teeth.
  5. The male bears well-developed hemipenis.
  6. The size of the body rangs from 16 mm (dwarf gecko: Sphaerodactylus ariasae) to 5.21 meters (green anaconda: Eunectes murinus).

The order Squamata includes the following thirteen families:

  • Family-1: Agamidae
  • Family-2: Gekkonidae
  • Family-3: Lacertidae
  • Family-4: Scincidae
  • Family-5: Anguidae
  • Family-6: Varanidae
  • Family-7: Typhlopidae
  • Family-8: Acrochordidae
  • Family-9: Boidae
  • Family-10: Colubridae
  • Family-11: Elapidae
  • Family-12: Hydrophiidae
  • Family-13: Viperidae

Family-1: Agamidae

  1. The family Agamidae contains over 350 species in 52 genera.
  2. They are commonly known as iguanian lizards, dragons or dragon lizards, distributed in Australia, southern Asia, and Africa.
  3. The body is scaly with well-developed legs and a moderately long tail.
  4. The average body size ranges from 4 to 6 inches (10 to 15 cm), while the tail is 8 to 12 inches (20 to 30 cm) long.
  5. They are ground-dwelling and arboreal species which inhabit tropical rainforests, mountain forests as well as deserts and steppes.
  6. They possess keeled scales, throat flaps or fans and middorsal crests.
  7. The males have more brightly colored than females.
  8. They are generally diurnal and their foods consist of insects and spiders, nestling birds, small reptiles or mammals, flowers or other vegetable matter.
  9. Most of them are oviparous.

Examples:  Laungwala long-headed lizard or Rajasthan toad-headed lizard (Bufoniceps laungwalaensis), Ground agama (Agama aculeata), Southern rock agama(Agama atra),etc.

image of Southern-rock-agama

Some popular and well-known lizards under the Agamidae family:

  1. Agama Lizard
  2. Bearded Dragon
  3. Common Gliding Lizard
  4. Changeable Lizard
  5. Earless Agamid
  6. Ground Agama
  7. Five-banded Gliding Lizard
  8. Water Dragon
  9. Green Crested Lizard
  10. Southern Rock Agama
  11. Red-headed Rock Agama
  12. Uromastyx
  13. Spotted Gliding Lizard

Family-2: Gekkonidae

  1. The members of the family Gekkonidae are called the common geckos.
  2. This family contains over 950 known species in 61 genera, occur globally.
  3. The size of the body ranges from 1.2 -10 inches. The Jaragua sphaero (Sphaerodactylus ariasae) is the smallest gecko which grows up to 0.63 inch in length while the largest gecko is the New Caledonian giant gecko (Rhacodactylus leachianus), grows more than 10 inches in length.
  4. They have short, somewhat flattened bodies with large heads and eyes.
  5. The limbs are well-developed with well-developed claws. In some species, the base or tips of toes bear expanded pad that permit adhesion to smooth surfaces.
  6. They are carnivorous and mainly feed on insects, worms but larger species eat small-sized birds, reptiles and mammals while some other take small amount of plant matter such as moss.
  7. They are oviparous and the female gecko lays 2 sticky white color eggs. The eggs hatch between one and three months.

Examples: Aaron Bauer's house gecko (Hemidactylus aaronbaueri), Tokay gecko (Gekko gecko), Andaman Islands day gecko (Phelsuma andamanense), Mourning gecko or common smooth-scaled gecko(Lepidodactylus lugubris), Narrow-tailed four-clawed gecko (Gehyra angusticaudata),etc.

image of Gekko gecko

Family-3: Lacertidae

(Wall lizards, Rock lizards, and their relatives)

  1. The members of the family are known as the wall lizards, true lizards, or sometimes simply lacertas which are native to Asia, Europe, Africa and the East Indies.
  2. It is a diverse family which contains approximately 300 species in 39 genera.
  3. They have small to medium-sized elongated body with conical head on distinct neck.
  4. The tail is moderately long and thick.
  5. The limbs are well-developed; the hind limbs are distinctly larger than the forelimbs.
  6. The back of the body bears small beaded scales while the belly contains square or rectangular scales.
  7. The body possesses different colors and patterns. In this case, the males show more spectacular colors than the females.
  8. The body size ranges from 8 inches (20 cm) to 20 inches (50 cm) in length.
  9. They prefer to live in deserts, forests, grasslands.
  10. Some species of lacertas eat insects, seeds and fruits but other takes almost only plant material.
  11. The lacertas reproduce during spring to early summer. The female builds a hole in the ground and lays 10-20 eggs at a time. The eggs hatch between three or four months.

Examples: Atlantic Lizard (Gallotia atlantica), Spanish algyroides, Spanish keeled lizard (Algyroides marchi), Greek rock lizard (Hellenolacerta graeca), Maltese wall lizard (Podarcis filfolensis), etc.

image of Atlantic Lizard (Gallotia atlantica)

Family-4: Scincidae

  1. The members of the family Scincidae are commonly called skinks. This family contains over 1500 known species under over 100 genera.
  2. The skinks have true lizard-like body with relatively small legs and long tapering tails.
  3. The size of the body of skink ranges from 7.5-76 cm (3.0-30 inches) in length. In this case, the body size of the smallest skink (Scincella lateralis) ranges from  7.5 to 14.5 cm (3.0 to 5.7 in) in length, on the other hand the largest skink is the Solomon Islands skink or  the prehensile-tailed skink (Corucia zebrata) which grows up to 76 cm (30 in) in length.
  4. They body of the skink is covered by smooth, shiny cycloid scales which makes the body shiny appearance.
  5. Most of the skinks are arboreal and diurnal. 
  6. Skinks are carnivorous and their food consists of various invertebrates such as flies, grasshoppers, beetles, crickets, and caterpillars, millipedes, centipedes, earthworms, slugs, snails, isopods, moths, small lizards and small rodents. But large species are herbivorous and they eat various types of fruits.
  7. Some skink species are egg layers while others are viviparous which gives birth to babies.

Examples: Inland snake-eyed skink (Cryptoblepharus australis), Noble snake-eyed skink (Cryptoblepharus exochus), Dark-sided emoia, dark-sided skink, dateline emoia (Emoia adspersa), Red-throated cool-skink, red-throated skink (Acritoscincus platynota), Kinghorn's snake-eyed skink (Austroablepharus kinghorni), Guinea lidless skink (Panaspis africanus), Alpine bog skink ( Pseudemoia cryodroma), etc.

image of Cryptoblepharus australis

Family-5: Anguidae

  1. The family Anguidae contains 112 species in 14 genera.
  2. They are small to large lizards with reduced or absent limbs.
  3. The body is elongated with size ranges from 10 cm to 1.5 meters in length.
  4. They are distributed in North Africa, North and South America, Europe, and Asia.
  5. They occur in wide variety of habitats including coastal dunes, desert, grasslands, pine flatwoods, cloud forest, pine-oak forest, tropical wet forest, etc.
  6. The anguids are carnivorous or insectivorous, and the small sized lizard mainly feeds on insects while the larger species hunt amphibians and small reptiles.
  7. They exhibit various body colorations; many have bronze or brown shade, but some have more striking coloration with boldly patterned.
  8. Osteoderms (small bony elements) are present below the dorsal and ventral scales.
  9. Generally, a lateral fold present which separates the dorsal and ventral scales on each side.
  10. Most species have external ear opening but many species do not have it.
  11. In some species, the tail is shorter than the body but some have much longer tail.
  12. They are both viviparous and oviparous. Among them, some give birth to one to two babies while some lay eggs.

Examples: Common slowworm (Anguis fragilis), Peloponnese slowworm (Anguis cephallonica), Hainan glass lizard (Dopasia hainanensis), Wegner's glass lizard (Dopasia wegneri), Slender glass lizard (Ophisaurus attenuatus), etc.

image of Common-slowworm

Family-6: Varanidae (Monitor Lizards)

  1. The members of the family Varanidae are commonly referred to as the monitor lizards or simply monitors.
  2. The body is sturdy with a small head, long neck and long powerful tails.
  3. The komodo dragon (Varanus komodensis) is the largest species which grows up to 3.1 m long with 250 kg in weight while the smallest species is Pygmy goanna (Varanus brevicaudatus) which can grow up to 23 cm in length.
  4. The tail is long, muscular with a formidable weapon.
  5. The family Varanidae comprises over 60 species under the genus Varanus.
  6. They are distributed in central and southern Asia, Africa, islands of Malaysia and Indonesia, Australia and Papua New Guinea.
  7. They inhabit wide variety of habitats including dry deserts, grasslands, lush forests and swamps.
  8. They eat wide variety of foods; some eat mollusks and fruits, other take lizards, eggs, and young mammals and birds while komodo dragon hunts large mammals such as buffalo, monkeys, adult birds, wild pigs and deer. 
  9. During the breeding season, after mating, the female lays two to sixty eggs in underground burrows, or termite nests or ground-built bird nests. The eggs need to hatch four to eight months.

Examples: Savannah monitor (Varanus exanthematicus), Desert monitor (Varanus griseus), Komodo dragon (Varanus komodoensis), Peach throat monitor (Varanus jobiensis), Water monitor (Varanus salvator), Emerald tree monitor (Varanus prasinus), Crocodile monitor (Varanus salvadorii), Lace monitor (Varanus varius), etc.

image of Water-monitor-(Varanus salvator)

Family-7: Typhlopidae

  1. They are commonly known as blind snakes with currently over 200 species under 18 genera.
  2. They are distributed in Asia, Africa, the Americas, Australia and many islands.
  3. They have tube-shaped smooth and shiny bodies with the body, head, and tail have about the same diameter.
  4. The Schlegel's beaked blind snake or Schelegel`s giant blind snake (Afrotyphlops schlegelii) is the largest species, grows up to 95 cm in length but most species are less than 20 cm long.
  5. The belly does not contain scales; eyes are dot-like, covered by head shields.
  6. All typhlopids have transversely placed movable maxillae with teeth and toothless dentaries.
  7. All members of typhlopidae possess tracheal lung and the left lung is commonly absent.
  8. They are very fast eaters, and their main food consist of ants, termites, worms, and other small invertebrates.
  9. Most  typhlopids are oviparous but Typhlops diardi is ovoviviparous.
  10. Small sized species lay few eggs while larger species lay more than fifty eggs.

Examples: Beaked worm snake, beaked blind snake, or beak-nosed worm snake(Grypotyphlops acutu),  Brahminy blind snak (Indotyphlops braminus),  Long-tailed blindsnakes, long-tailed blind snakes, Arboreal blind snake (Ramphotyphlops angusticeps), Christmas Island blind snake (Ramphotyphlops exocoeti), etc. 

image of Brahminy-blind-snake

Family-8: Acrochordidae

  1. The members of the family Acrochordidae are commonly known as wart snakes,   Java wart snakes, , elephant trunk snakes, file snakes or dogface snakes.
  2. The skin bears numerous small, granular scales, which project from the skin giving it a rugose texure; hence their other common name, the file snakes.
  3. The scales do not overlap and the interstitial skin forms bristle-tipped tubercles.
  4. The head and the body are covered with small, granular or  tuberculate, juxtaposed scales.
  5. Eyes are located on the top rather than the sides of their heads.
  6. They do not have broad belly scales found on most other snakes.
  7. 7.  They are distributed in Southeast Asia, the Philippines, Indonesia,  New Guinea,   Mussau Island, Guadalcanal Island, the Solomon Islands, etc.
  8. The family Acrochordidae contains 3 species in one genera and the adult Acrochordids grows between 60 cm and 2.43 m in length with over 10 kg in weight.
  9. They inhabit diverse habitats including freshwater rivers, lakes, mudflats, mangroves, reefs, and open seas.

Examples: Arafura File Snake (Acrochordus arafurae), Little wart snake (Acrochordus granulatus), Elephant trunk snake, Javan file snake(Acrochordus javanicus), etc.

image of Arafura File Snake (Acrochordus arafurae)

Family-9: Boidae

  1. The members of the family Boidae are commonly known as Boas and pythons,
  2. The family contains recognized 49 species in 12 genera, has a wide spread distribution with great diversity in the tropics, some species however, live in cool temperate habitats.
  3. The size of the body ranges from 1.2–25 ft (0.37–7.7 m) in length with up to over 145 kg in weight.
  4. Boas are typically stout bodied and short tailed with no teeth while pythons have teeth.
  5. They inhabit variety of habitats including loose sand, burrows, forest, grasslands, savanna, and various freshwater habitats.
  6. Boas give birth to young whereas python lays eggs.
  7. Both have two lungs instead of the usual one and most boids have vestigial hind limbs. The vestigial hind limbs of the boids are apparently functional structure used in courtship.
  8. Boids are primarily ambush hunters and consume vertebrate prey like, lizards, other snakes, small mammals, etc.
  9. All boids are live-bearer and give birth to live young.

Examples: Amazon Basin emerald tree boa (Corallus annulatus), Rainbow boa (Epicrates cenchria), Green anaconda (Eunectes murinus), Cuban boa(Chilabothrus angulifer), etc.

image of Green anaconda (Eunectes murinus)

Family-10: Colubridae

  1. They are commonly known as colubrids which are the advanced snakes often referred to as a trash-can taxon.
  2. It is the largest snake family containing a variety of snakes with  249 genera comprising almost 75 percent of all the world's snake species.
  3. Their body size ranges from about 6 inches (15.2 cm) to  144 inches (3.7 meters) in length.
  4. They have single or two lungs with the left one extremely reduced.
  5. Usually, the belly scales are as wide as the body.
  6. Teeth are normally present on the maxillary, palatine, pterygoid and dentary or lower jaw but are never found on the premaxillary.
  7. Most species have solid teeth without groves without any venom glands connection.
  8. Some species though venomous, none of these have true fangs.
  9. Colubrids eat wide variety of foods and their food consists of mammals, lizards, baby turtles, frogs and toads, fishes, tarantulas, earthworms, scorpions, some other insects, etc.

Examples: Graham's crayfish snake (Regina grahamii), Queen snake( Regina septemvittata), Dary's burrowing snake (Adelphicos daryi),  Black-collared snake (Drepanoides anomalus),  Banded cat-eyed snake(Leptodeira annulata),etc. 

image of Black-collared snake (Drepanoides anomalus)

Family-11: Elapidae

  1. The members of the family Elapidae are commonly known as elapids.
  2. This family comprises of some 360 species in 56 genera, endemic to tropical and subtropical regions around the world.
  3. They have long and slender body with smooth scales.
  4. The head is covered with large shields and eyes with round pupils.
  5. They have a wide range of body sizes. The world`s longest venomous snake is the king kobra (Ophiophagus hannah) which grows up to 5.85 m (19.2 ft) in length.
  6. Most elapids are oviparous and they lay eggs.

Examples: South Andaman krait (Bungarus andamanensis), Indian cobra, spectacled cobra (Naja naja), king cobra (Ophiophagus hannah), Goldie's tree cobra (Pseudohaje goldii), Rough-scaled snake (Tropidechis carinatus), Lake Cronin snake (Paroplocephalus atriceps), etc.

image of Naja naja

Family-12: Hydrophiidae

  1. The members of the family Hydrophiidae are commonly known as sea snakes.
  2. The family contains 69 described species in 17 genera, distributed in the Indian and Pacific Oceans.
  3. Sea snakes produce venom which they injects through fixed fangs, positioned at the front of the mouth.
  4. The tails are vertically flattened to act as paddles and help propel them through the water.
  5. The body is laterally compressed which gives eel-like appearance.
  6. The body size ranges from 120-150 cm (3.9 - 4.9 ft) in length. The largest sea snake is the Hydrophis spiralis, which grows up to 3 m (9.8 ft) in length.
  7. They have relatively small eyes with a round pupil.
  8. They are carnivorous and mainly feed on fish and occasionally young octopus.
  9. Most are ovoviviparous and give birth to young babies.

Examples:  Horned sea snake, Peron's sea snake, and the spiny-headed seasnake (Hydrophis peronii), Short-nosed sea snake (Aipysurus apraefrontalis), Tokes's sea snake (Hydrophis stokesii), Turtle-headed sea snake or egg-eating sea snake(Emydocephalus annulatus), Beaked sea snake, Hook-nosed sea snake, Common sea snake (Enhydrina schistosa), Grey's mudsnake, Mangrove seasnake (Ephalophis greyae), Bighead sea snake, Annandale's sea snake (Hydrophis annandalei), etc.

Family-13: Viperidae

  1. Vipers are probably the best known of all snakes.
  2. They have broad, roughly triangular heads and most are also heavy-bodied with relatively short, slender tails.
  3. They produce venom, which they inject using long, hinged fangs at the front of their mouth.
  4. Vipers are diverse group occurring on all continents except Australia.
  5. They include aquatic to arboreal species, range from sea level to the tree line, and occur in near rainless desert to evergreen rain forest.
  6. They prey on invertebrates and vertebrates.
  7. Pit vipers, uniquely characterized by a local pit organ on each side on the heads which include them to detect the body heat of their prey.

Examples: Gloyd's cantil, Gloyd's moccasin southern cantil (Agkistrodon howardgloydi), Central American jumping pit viper (Atropoides mexicanus), Common lancehead (Bothrops atrox),  Chasen's mountain pit viper (Garthius chaseni), Sri Lankan hump-nosed viper (Hypnale nepa), etc.

image of Common-lancehead

Order-4: Crocodylia

  1. The order Crocodylia includes the alligators, gharials, caimans and crocodiles.
  2. They are the only ectothermic reptiles with four-chambered heart.
  3. They are the predatory semi-aquatic reptiles, commonly called crocodilians. 
  4. They have long flattened snouts with laterally compressed tails.
  5. The body is long with large and long head.
  6. Jaws are powerful with sharp teeth.
  7. They have well-developed limbs. In this case, hind limbs are heavier and larger than the forelimbs.
  8. The fore feet are un-webbed with five digits while the hind feet are strongly webbed with four fully developed digits.
  9. They are carnivorous and their food consists of mainly insects, crustaceans, molluscs, birds, fishes, reptiles and mammals.
  10. They are oviparous and some crocodiles make the mound-nests of vegetation and soil while other digs their nests in loose soils using their head and limbs.
  11. Females guard their nests and assist the young to escape from their eggshells and the nests.
  12. The body size of the crocodilians range from 1 meter to 7 meters. In this case, the saltwater crocodile grows up to 7 m with 2,000 kg in weight.

The order Crocodylia includes the following three families:

  • Family-1: Crocodylidae
  • Family-2: Gavialidae
  • Family-3: Alligatoridae

Family-1: Crocodylidae

  1. The members of the family Crocodilidae are commonly known as crocodiles.
  2. The family Crocodylidae contains a total of 15 species.
  3. They are all aquatic but frequently bask in the sun on shore.
  4. They have long, strong tail which is used for swimming and is also powerful weapon of offense or defense.
  5. Each jaw bear 14-24 sharp teeth, used for seizing but not for chewing.
  6. They lay large, hard-shelled eggs either in a shallow excavation on a sandy shore or in a nest piled by the mother.
  7. The head is long and narrow with more V-shaped snouts.
  8.  The upper jaw of alligator is wider than its lower jaw while in crocodiles, the lower and upper jaws are the same width.

Examples: Mugger crocodile (Crocodylus palustris), Saltwater crocodile (Crocodylus porosus), Freshwater crocodile (Crocodylus johnsoni), Borneo crocodile (Crocodylus raninus), Cuban crocodile (Crocodylus rhombifer), Siamese crocodile (Crocodylus siamensis), Dwarf crocodile (Osteolaemus tetraspis), Central African slender-snouted crocodile (Mecistops leptorhynchus), etc.

image of Crocodylus siamensis

Family-2: Gavialidae

  1. The family Gavialidae contains only two extant species; the gharial (Gavialis gangeticus), which is native to India and Nepal and the false gharial or Malayan gharial (Tomistoma schlegelii), native to Peninsular Malaysia, Borneo, Sumatra, and Java.  
  2. They are the large semi-aquatic reptiles having much thinner and elongated snouts.
  3. They can grow up to 6.5 meters in length.
  4. The body is strongly armored with nuchal and dorsal scutes.
  5. They inhabit deep and fast flowing rivers.
  6. The female reaches sexual maturity at the age of 10 years.
  7. They are carnivorous and entirely feed on fish, insects and frogs.
  8. They are oviparous and the female lays 30-50 eggs in their prepared nests.
  9. They have partially webbed fingers and toes.  

Examples: Gharial (Gavialis gangeticus),  False gharial (Tomistoma schlegelii), etc.

image of Gharial-(Gavialis gangeticus)

Family-3: Alligatoridae

  1. The family Alligatoridae includes the alligators and caimans with extant 4 genera and 8 species.
  2. The head is wider and shorter with larger, broader and more obtuse snouts.
  3. They can adept to survive colder temperature than crocodylids.
  4. They are less aggressive than crocodylids.
  5. They can grow up to 18-20 feet in length.
  6. The fourth tooth of the lower jaw fit inside those of upper jaw.

Examples: American alligator (Alligator mississippiensis), Chinese alligator (Alligator sinensis), Black caiman (Melanosuchus niger), Yacare caiman (Caiman yacare), Smooth-fronted caiman (Paleosuchus trigonatus), etc.

image of American alligator (Alligator mississippiensis)

Concluding Remarks

Most of the reptiles, particularly the snakes and lizards are beneficial. Reptiles play as an important part of the food webs in most ecosystems. They constitute one of the most important biological control agents through feeding on harmful rodents and insects. They also prevent overpopulation and provide food for hungry predators. Snakes are major predators of rodents. Some herbivorous reptile species play a key role for the dispersion of seed and also act as pollinators. Besides these, many people regularly harvest the turtles, lizards, snakes, and crocodiles as food for local consumption in many countries. Some snakes, however, prey on eggs of game and other birds in their breeding seasons. Skin of crocodiles and some snakes are used for fancy leather to make vanity bags, shoes, and other leather goods. At present, many species have gone to extinct due to over exploitation and various illegal human activities. The absence of them allows agricultural pest populations to explode. Some conservation measures should be taken to protect the valuable reptile species from their extinction near the future.   

Amphibia: Characteristics, Classification and Examples

The class Amphibia belongs to the subphylum Vertebrata of phylum chordata. All the representatives of Clssa Amphibia are ectothermic, tetrapod vertebrate animals which inhabit a wide variety of habitats including terrestrial, arboreal, fossorial,  or freshwater aquatic ecosystems. The name amphibian is derived from Greek word "amphibious" which means “living a double life”. Because some species are permanent land dwellers, while other species show an entirely aquatic mode of life. There are about 8100 known living amphibians, of which nearly 90% are frogs. Amphibians first appeared about 340 MYA (million Years Ago) ago during the Middle Mississippian Epoch of the Paleozoic Era.

The representatives of modern amphibians are frogs, toads, newts, salamanders and caecilians, show several unique characteristic features. They have a wet skin and depend greatly on cutaneous as a secondary respiration but some small terrestrial salamanders and frogs  do not have lungs, entirely depend on their skin for their respiration.  They also contain green rod in their retina to differentiate colors, two-part teeth and a dual-channeled hearing system.

Paedophryne amauensis is a species of frog from New Guinea which grows up to only 7.7 mm in length while the largest living amphibian is the South China giant salamander (Andrias sligoi) reaching a length of 1.8 m (5 ft 11 in). The science which deals with the study of amphibians is called batrachology.

General Characteristics Features of the Class Amphibia

  1. Amphibians are ectothermic vertebrate animals.
  2. They inhabit is a wide variety habitats including terrestrial, arboreal, fossorial, or freshwater aquatic ecosystems.
  3. The body has two parts: head and neck; in some cases, tail and neck may or may not present.
  4. They have soft moist pigmented and glandular skin which does not contain any scales but the skin of caecilians contains scales. In this case, skin is smooth and rough and glands keep the skin moist. 
  5. Mouth is large which contains protusible tongue and homodont type teeth.
  6. There are two pairs of limbs which are used for locomotion.
  7. The body does not bear paired fins but unpaired fins might be present.
  8. They perform respiration through skin and lungs. But larval forms respire through the gills. In some case, gills might be present externally in the some adults.  
  9. Digestive system is complete and the heart is three chambered with two auricles and one ventricle; portal system is well-developed.
  10. The excretory system consists of mesonephric kidney. The excretion is ureotelic and the excretory waste products are ammonia and urea.
  11. Brain is poorly developed with 10 pairs of cranial nerves.
  12. The sexes are separate and they usually perform external fertilization. In case for salamanders, the fertilization is internal.
  13. They are egg layers and usually breed in water bodies. The male does not possess copulatory organs.
  14. Indirect development occurs. In this case, tiny larval forms with no legs or lungs are seen, known as tadpole larva which is transformed into adult through metamorphosis. In this case most larvae are herbivorous, some omnivorous or carnivorous. 
  15. The lateral line is seen during their larval stage.
  16. The notochord is present at embryonic stage which does not persist and transforms  into vertebra at adult stage.

Classification of Amphibia

Gladwyn  Kingsley Nobel (1954), described the classification of Amphibia in his book “The Biology of Amphibia”. He classified the Class Amphibia into two sub-classes, namely Stegocephalia and Lissamphibia, of which Stegocephalia includes all extinct members and other subclass Lissamphibia includes the living members.

Subclass-1: Stegocephalia (extinct)

[Gr. Stegos=cover+ kephale=head]

  1. They were extinct typically tailed salamandriform amphibians.
  2. They had well-developed limbs and sometimes of large size.
  3. Skin covered by ossified scales and bony plates.
  4. Limbs were pentadactyle (five digits) types.
  5. Skull had solid bony roofs which possess two pairs of opening for eyes and nostril.
  6. They were found between Permian to Triassic period of the Paleozoic and Mesozoic eras.

Subclass Stegocephalia is further divided into the following three orders:

  • Order-1: Labyrinthodontia
  • Order-2: Phylospondyli
  • Order-3: Lepospondyli

Order-1: Labyrinthodontia

(Gr. Labyrinthos=maize +odontos=teeth)

  1. They were the most primitive tetrapods and oldest known tetrapods, called as stem Amphibia.
  2. They occurred in both water and land.
  3. They showed characteristic of crocodiles and salamander.
  4. Their skulls had much bony elements than the modern amphibian.
  5. Skull and face completely covered by bones.
  6. Both the jaws had enlarged teeth with greatly folded dentine layer.
  7. They had equal-sized limbs with well-defined tail
  8. They lived from Lower Carboniferous to the Triassic periods.
  9. They inhabited in water.

Order Labyrinthodontia is divided into the following three suborders:

  • Suborder-1: Embolomeri
  • Suborder-2: Rachitomi
  • Suborder-3: Steropondyli

Suborder-1: Embolomeri

  1. They had fish-like appearance, become visible in the Carboniferous period, and became plentiful during the Pennsylvanian period of Palaeozoic Era and extinct at the end of Triassic period of Mesozoic Era.
  2. Some had superficially crocodile-like appearance.
  3. The vertebrae were embolomerous. In this case, an anterior inter-centrum and a posterior pleurocentrum combine to form circular structure.
  4. They had teeth with dentine that infolded at the base into labyrinthine grooves.
  5. They had increased-size shoulder girdle.
  6. The pelvic girdle did not directly attach to the vertebral column. In this case, it held in place via ligament.
  7. The skull had two or three occipital condyles.

Examples: Eogyrinus attheyi, Loxomma, Palaeogyrinus, etc.

image of Eogyrinus

Eogyrinus sp.

Suborder-2: Rhachitomi

  1. They flourished during the Permian and Triassic Period of geological time scale.
  2. The skull had two or three occipital condyles.
  3. They had large depressed skull with large interpterygoid vacuities and otic notch.
  4. They were about 150 cm long having short powerful legs with five toes.
  5. The vertebrae were rhachitomous type with a semilunar wedge-like inter-centrum and one or two posterior pleurocentra.

Examples: Eryops, Cacops

image of Eryops

Eryops

Suborder-3: Steropondyli

  1. They lived at Triassic period of Mesozoic era.
  2. The skull had two occipital condyles.
  3. Vertebrae with inter-centrum but pleurocentrum reduced or absent.

Examples: Capitosaurus.

image of Capitosaurus

Capitosaurus.

Order-2: Phyllospondyli

[Gr. Phylon=leaf +spondylos=vertebrae]

  1. They had salamander-like appearance.
  2. The skull had two occipital condyles.
  3. Vertebrae were slightly flattened type.
  4. The nerve cord and notochord remained in the same cavity.
  5. The skull was broad with heavily roof.

Examples: Branchiosaurus salamandroides

image of Branchiosaurus salamandroid

Branchiosaurus salamandroides

Order-3: Lepospondyli

[Gr. Lepos=circular+ spondylos=vertebrae]

  1. They flourished at late Palaeozoic period of geological time scale.
  2. The body was small which ranged from a few inches to a few feet in size.
  3. They had salamander-like or a few superficially snake-like appearance.
  4. They had lepospondylous type vertebrae. In this case, centra formed directly of bone around notochord, not preceded by cartilage. Centra looked-like spool, neural arch attached to centrum.
  5. Vertebrae consisted of only one bone.
  6. Ribs attached with column between vertebrae.

Order Lepospondyli is divided into the following three suborders:

  • Suborder-1: Adelospondyli
  • Suborder-2: Aistopoda
  • Suborder-3: Nectridea

Suborder-1: Adelospondyli

  1. They lived at Permian period of geological time scale.
  2. The neural arches loosely attached to centrum with suture.
  3. A pair groove situated at each vertebra ventral-laterally.
  4. The skull was incompletely roofed; circumorbital bones disappeared.
  5. Gill breathing respiration occurred in adult.

Example: Lysorophus.

image of Lysorophus

Lysorophus.

Suborder-2: Aistopoda

  1. The body was elongated, most of them were feetless.
  2. They had long skull with clear transverse process.
  3. Ribs were peculiar type.

Example: Ophioderpeton

image of Ophioderpeton

Ophioderpeton

Suborder-3: Nectridea

  1. Skull was triangular type.
  2. Broad neural and haemal process were present at the tail region.
  3. They had small arms and jaws.
  4. They had long flattened tails which are used for swimming.
  5. Shoulder girdles were wide and possess a short rear extension.
  6. Hind limbs were well-developed with five toes on each leg.
  7. They had slightly reduced forelimbs.

Example: Urocordylus

image of Urocordylus

Urocordylus

Subclass-2: Lissamphibia

  1. All modern living amphibians belong to the subclass Lissamphibia.
  2. The body possesses two types of skin glands such as mucous and granular.
  3. One pair of occipital condyles are present.
  4. Gonad and fat bodies are linked together.  
  5. The inner ear contains double-channeled sensory papillae. 
  6. They have the ability to elevate the eyes using the levator bulbi muscle.
  7. A special type of visual cell, known as green rods is present.
  8. Centram (plural: centrum) of the vertebrae are cylindrical type.
  9. Small and simple pedicellate teeth are present. In this case, crowns are separated from the roots by fibrous tissue.
  10. Lack of posterior skull bones. 
  11. The skull possesses widely separated and small pterygoid bones.
  12. Dermal bony plates over the skin are absent.

The subclass Lissamphibia includes the following three orders of living amphibian:

  • Order-1: Gymnophiona/Apoda
  • Order-2: Caudata
  • Order-3: Salientia/Anura

Order-1: Gymnophiona/Apoda

[Gr. Gumnos=naked+ophioneos=snake /Apoda(Gr. A=none+podos=foot]

  1. The body is elongated worm/snake like with no legs.
  2. The representatives of this order are blind and inhabit in burrows.
  3. The tail is short or absent and the cloaca is terminal.
  4. Protrusible tentacles are present between nostril and eyes.
  5. Protusible copulatory organ is present in the males.
  6. Fertilization is either internal or external. In Typhlonectess, fertilization is external.
  7. Eyes do not bear eye lids.
  8. Skin bears numerous transverse folds which contains dermal scales.
  9. Compact skull which is roofed by bones.

Examples: Ichthyophis glutinosus, Typhlonectes compressicauda, Uraeotyphlus oommeni, etc.

image of Typhlonectes compressicauda

Typhlonectes compressicauda

Family-1: Caecilidae

  1. They inhabit in burrows of moist soil.
  2. Some members lay eggs in moist soil while some other give birth to live babies. The eggs hatch into larvae which live in leakage in soil or streams.
  3. The body is generally slender and can grow up to 1.5 meters in length.
  4. The body colors vary from dark bluish slate to light gray with visible annuli.
  5. The skull possesses relatively few bones.
  6. The body does not have tail and the mouth is recessed beneath the snout.

Examples: Caecilia abitaguae, Caecilia albiventris, Oscaecilia bassleri, Oscaecilia elongate,etc.

image of Oscaecilia elongate

Oscaecilia bassleri

Family-2: Typhlonectidae

  1. They are commonly called aquatic caecilians.
  2. They inhabit in water for entire life.
  3. Eyes are very prominent.
  4. They are viviparous and give birth to live babies.
  5. The body length ranges from 140-750 mm.
  6. They possess tracheal lungs and narial plugs.
  7. The lower jaw bears two series teeth.
  8. They lack annular scales as well as secondary annuli.
  9. Some species are fully aquatic.
  10. They have compressed body and dorsal fins.

Examples:  Chthonerpeton arii, Chthonerpeton braestrupi, Nectocaecilia petersii, Typhlonectes natansetc.

image of Typhlonectes natans

Typhlonectes natans

Family-3: Ichthyophidae

  1. They are commonly known as fish caecilians or  Asiatic tailed caecilians.
  2. They are distributed in South and Southeast Asia.
  3. The body bears numerous scales.
  4. The body has tail and mouths are not recessed under their head.
  5. For closing the jaw, two sets of muscles are present.
  6. They are oviparous and they lay eggs in cavities in moist soil.
  7. The eggs hatch into larvae which inhabit streams or underground leakages. In this case, the females take care for their eggs until hatching.

Examples: Ichthyophis acuminatus, Ichthyophis alfredi, Uraeotyphlus gansi, Uraeotyphlus interruptus, etc.

image of Uraeotyphlus interruptus

Uraeotyphlus interruptus

Order-2: Caudata / Urodela

[L. cauda=tail) / Urodela (Gr. Oura=tail+delos=visible]

  1. The body is divided into head, trunk and tail.
  2. They have lizard-like appearance.
  3. They are also called Urodela due to the presence of tail.
  4. Both the fore limbs and hind limbs are equal in size.
  5. The body does not possess scales and tympanum.
  6. The gills are presents in some adult forms.
  7. Some species show neoteny and paedogenesis.
  8. Males do not have copulatory organ.
  9. Both jaws bear teeth. 
  10. They are usually oviparous and the larvae are aquatic.

Suborder-1: Cryptobranchoidea

  1. They are also known as primitive salamanders.
  2. Premaxillary spines are reduced.
  3. Gills and eyelids are not present in adult stage.
  4. Fertilization is external and cloacal glands are complex type.
  5. Some lead fully aquatic life.

Family-1: Hynobiidae

  1. They are known as the Asiatic salamanders.
  2. They are found all over Asia, and in European Russia.
  3. Teeth on the vomer are V shaped.
  4. Premaxillary fontanelles are broad.
  5. Some species perform external fertilization while other reproduces internally.
  6. They show parental care for their babies.
  7. The matured female lays up to 70 eggs at a time. 
  8. Some species have very reduced lungs or without lungs.
  9. Sometimes, the larvae possess reduced external gills.

Examples: Hynobius abei,  Hynobius abuensis, Afghanodon mustersi, Batrachuperus  karlschmidti, etc.

Family-2: Cryptobranchidae

  1. They are fully aquatic and commonly known as the giant salamanders.
  2. They can grow up to 1.9 m (5.9 ft) in length and live up to 50 years.
  3. They are nocturnal and feed on fish and crustaceans at night.
  4. Maxillary and premaxillary teeth are arranged parallel.
  5. Eyes are small with no eyelids.
  6. Lateral line sensory organ is present.

Examples: Cryptobranchus alleganiensis, Andrias scheuchzeri, Chunerpeton tianyiensis, etc.

image of Chunerpeton sp

Chunerpeton  sp

Suborder-2: Ambyostomoidea

  1. The body is slender and lizard-like with blunt snouts and short limbs.
  2. Both larvae and adults possess tail.
  3. Front limbs bear four toes and five toes on their hind legs.
  4. They are oviparous and typically lay eggs in water.
  5. The eggs hatch into aquatic larvae.
  6. Prevomer is reduced and premaxillary spines are very large.
  7. Parasphenoid does not contain teeth.
  8. Vertebrae are Amphicoelous type.
  9. Cartilaginous cross-bar is present behind the hyoid apparatus between the two ears.

Family-1: Ambystomidae

  1. They are also known as mole salamanders.
  2. The body is small to moderate size, with 35 cm in length.
  3. They usually have well-developed lungs.
  4. This family contains about 32 species.
  5. Palatine bones do not contain any teeth while the vomerine teeth are present.
  6. Most of the species do not contain larval stage but, Ambyostoma tigrinum show larval stage (Axolotl) in their entire life. This process is known as Neoteny.

Examples: Ambystoma tigrinum, Ambystoma amblycephalum, Ambystoma taylori, etc.

image of Ambystoma tigrinum

Ambystoma tigrinum

Suborder-3: Salamandroidea

  1. They are also referred to as advanced salamanders, found worldwide.
  2. They are aquatic, semi-aquatic and terrestrial.
  3. The body possesses two pairs of limbs.
  4. They have small to moderate size body with up to 35 cm in length.
  5. They have usually well-developed lungs.
  6. Fertilization is internal through the use of a spermatophore.
  7. Both juveniles and adults possess lungs.

Family-1: Salamandridae

  1. This family consists of true salamanders and newts with currently 74 known species.
  2. They have very granular skin with the number of poison glands.
  3. They do not contain nasolabial grooves.
  4. The tail is long and the body has patterns of bright and contrasting colors.
  5. Limbs are well-developed; the fore limbs possess four toes while five toes on the hind limbs (most cases).
  6. The size of the body varies from 3 to 12 inches (7 to 30 cm) in length.
  7. They are viviparous and give birth to live babies.

Examples: Calotriton arnoldi, Cynops chenggongensis, Chioglossa lusitanica, Salamandrina terdigitata, etc.

image of Chioglossa lusitanica

Chioglossa lusitanica

Family-2: Amphiumidae

  1. They are also known as amphiumas, conger eels, congo snakes.
  2. The family Amphiumidae contains 3 species under one genus.
  3. They are large, aquatic eel-like salamanders.
  4. The body is elongate with generally grey-black in color.
  5. They can grow up to 116 cm (46 in) in length.
  6. The legs are very small and merely vestigial with up to about 2 cm (0.79 in) in length.
  7. Premaxillae are fused.
  8. Limbs and toes are reduced with 3, 2, or 1 toe per foot.
  9. They have laterally compressed tail which makes up one third of the total body length.
  10. They can live up to 27 years and can also grow up to three years without food.
  11. External gills are present in larval forms which disappear after about four months and the adult forms possess lungs.
  12. The body also contains one pair of gill slits which never disappears.
  13. Fertilization is internal and the female lays eggs on land.
  14. Females take care for their eggs and the eggs hatch into short-lived aquatic larvae.

Examples: Three-toed amphiuma (Amphiuma tridactylum), Two-toed amphiuma (Amphiuma means)One-toed amphiuma (Amphiuma pholeter), etc.

image of Amphiuma tridactylum

Three-toed amphiuma (Amphiuma tridactylum)

Family-3: Plethodontidae

  1. The family Plethodontidae consists of about 478 species in 28 genera.
  2. They are known as lungless salamanders. In this case, they perform respiration through their skin and tissues lining their mouths.
  3. Naso-labial groove is present which is present between the nostril and upper lip.
  4. They inhabit a wide variety of habitats including stream, fossorial terrestrial, arboreal, and cave habitats.
  5. Pterygoid is absent while the otic and occipital elements are fused.
  6. The body is elongate with up to 60 vertebrae.
  7. Teeth possess a distinct crown and pedicel.
  8. Males members have a mental gland.
  9. Fertilization is internal with direct development occurs.
  10. They possess four limbs with four toes on the fore limbs and five toes on the hind limbs.
  11. They lay eggs on land and hatch into young already possessing an adult body form.

Examples: Peter's climbing salamander (Bolitoglossa), Splay-foot salamanders (Chiropterotriton), Hidden salamanders(Cryptotriton), etc.

image of Bolitoglossa

Peter's climbing salamander (Bolitoglossa)

Suborder-4: Proteida

  1. They are the aquatic salamanders with persistent long filamentous external gills.
  2. They have two pairs of reduced limbs with three toes on each forelimb and two on each hind limb.
  3. The body is elongate with depigmented skin and degenerate eyes.
  4. The skull is mainly cartilaginous.
  5. Eyelids and lungs are absent.
  6. The body also bear a caudal fin.
  7. They have moderately large-sized body reaching up to 30 cm in length.
  8. They breed in spring and their fertilization is internal.
  9. They lay eggs which are attached to the undersides of logs and stones.
  10. Both male and female guard the eggs until hatching.
  11. During early summer, eggs hatch into larvae and require 4 to 6 years to reach sexual maturity.

Family-1: Proteidae

  1. They are exclusively aquatic salamanders, commonly known as Mudpuppies, Waterdogs, Olms, etc.
  2. The family Proteidae consists of 6 species in 2 genera.
  3. The body bears large, red, filamentous, external gills.
  4. Laterally compressed tail fins are present.
  5. They inhabit wide variety of habitats including lakes, rivers and streams or caves.
  6. They are distributed in Europe and North America.

Examples: Alabama waterdog (Necturus alabamensis), Gulf Coast waterdog (Necturus beyeri), Neuse River waterdog (Necturus lewisi),etc.

image of Necturus lewisi

Necturus lewisi

Suborder-5: Sirenoidea

  1. The body is small to very large with up to 100 cm in length.
  2. They have only anterior pair of limbs.
  3. External gills are present throughout the entire life.
  4. They inhabit lowland waters.
  5. Angular bone is fused with prearticular bone in lower jaw.
  6. Fertilization is external.
  7. Eyelids are absent.

Family-1: Sirenidae

  1. The body is eel-like with only forelimbs.
  2. Three pairs of external gills are present.
  3. The body length ranges from 9.8–37.4 in (25–95 cm).
  4. They are omnivorous and mainly feed on worms, shrimps, small snails, and filamentous algae.
  5. During dry season, they can able to burrow into mud and enclose themselves creating a cocoon of mucus for surviving the drought periods. At this time, they perform respiration with their small but functional lungs.
  6. The heart contains an interventricular septum.
  7. Males builds a nest for their offspring and engage in parental care.

Examples: Habrosaurus dilatusH. prodilatus, Noterpeton bolivianum, Siren simpsoni, etc.

Order-3: Salientia / Anura

[L. salere =to jump]

  1. The order salientia is also known as Anura which consists of the animal-like frogs, toads, and tree toads.
  2. This order contains about 5,400 known living species.
  3. The head and trunk are united together.
  4. In adult stage, they do not have tails.
  5. Hind limbs are stout and larger in size with highly muscular which are used for jumping, leaping, and swimming.
  6. Lung is present in adult form but the larval form contains gills for respiration.
  7. Tympanum is present and the eyelids are well-developed.
  8. Skeleton lacks ribs and the pectoral girdle is reduced.
  9. Vertebrae are few in number and last vertebra forms a slender urostyle.
  10. The body is covered with loosely fitted skin with no scales.
  11. They usually perform external fertilization and the eggs are laid in water.

Family-1: Ascaphidae

  1. They are known as tailed frogs. In this case, the tail is the extension of the male cloaca. During the mating period, the tail is used to insert sperm into the female.
  2. They exhibit internal fertilization.
  3. The body is small and reaches about 0.98 to 1.97 in (2.5 to 5.0 cm) in length.
  4. They are mostly aquatic and prefer to live in fast-flowing streams with cobblestone bottoms.
  5. Adults also forage terrestrially during cool, wet conditions.
  6. They breed during the months from May to September.
  7. Females lay their eggs in strings under rocks in fast-moving streams.
  8. Eggs hatch into larvae which take one to four years to reach maturity.

Examples: Ascaphus montanus, Ascaphus truei , etc.

Family-2: Liopelmitidae

  1. The leiopelmatids are the relatively most primitive amphibians.
  2. They are strangely small frogs with only 2.0 inches (5 cm) in length.
  3. Most of females lay eggs in the moist soil under rocks or vegetation.
  4. Eggs hatch into tadpole larvae which nest in the back of the male frog.
  5. They can live up to 30 years or more with favorable conditions.
  6. Vertebrae are amphicoelous type.
  7. Tympanum is absent.
  8. Nine free presacral vertebrae are present.
  9. Interdorsal and interventral remain cartilaginous.

Examples: Archey's frog (Leiopelma archeyi ), Hamilton's frog (Leiopelma hamiltoni), Hochstetter's frog (Leiopelma hochstetteri), etc.

Family-3: Discoglossidae/ Alytidae

  1. They are commonly known as painted frogs or midwife toads.
  2. Eight presacral vertebrae are present.
  3. Vertebrae are ophisthocolous tyepe.
  4. Eyelids and tongue are present.
  5. Most species are endemic to Europe but three species are found in Nortwest Africa.

Examples: Alytes cisternasii , Alytes dickhilleni, Discoglossus galganoi , Latonia nigrivente, etc.

image of Discoglossus galganoi

Discoglossus galganoi

Family-4: Pipidae

  1. They are also known as tongueless frogs.
  2. The family Pipidae contains 41 species, found in South America and Africa.
  3. The body is flattened with completely webbed foot.
  4. The body size ranges from 1.6 to 7.5 inches (4 -19 cm) in length.
  5. A adult frog possesses lateral line sensory organ.
  6. They have highly modified ears which are used for producing and receiving sound underwater.
  7. The tongue or vocal cords are absent. In this case, they use larynx for producing sound.
  8. Eyelids are absent or poorly developed.
  9. Sacrum is fused to the urostyle.

Examples: Hymenochirus boettgeri, Pipa arrabali, Xenopus allofraseri

Family-5: Pelobatidae

  1. They are commonly known as the European spadefoot toads.
  2. The family  Pelobatidae contains six species in one genus.
  3. These species are native to Europe, western Asia, northwestern Africa, and the Mediterranean. 
  4. They are small to large-sized frogs reaching up to 3.9 inches (10 cm) in length.
  5. The tongue is pritrusible type.
  6. They inhabit deserts and other arid regions.
  7. They have stocky body with vertical pupils.
  8. They are mostly fossorial frogs which burrow in sandy soils using hardened protrusions on their feet.
  9. They lay eggs in temporary water bodies.

Examples: Eopelobates anthracinus, Eopelobates bayeri, Pelobates balcanicus, Pelobates varaldii, etc.

Family-6: Myobatrachidae

  1. They are commonly known as Australian water frogs or Australian ground frogs.
  2. The size of the body ranges from 1.5 cm (0.59 in) to 12 cm (4.7 inches) in length.
  3. They lay eggs in the moist sand.
  4. The eggs directly hatch into miniature frogs.
  5. They are either terrestrial or aquatic frogs.
  6. Eight presacral vertebrae are present.

Examples: Northern sandhill frog (Arenophryne rotunda), Bilingual frog (Crinia bilingua), Red-crowned toadlet (Pseudophryne australis), etc.

Family-7: Bufonidae

  1. The family Bufonidae contains over 570  known species under 52 genera.
  2. The members of the family Bufonidae are known as true toad.
  3. They inhabit a wide variety of habitats from arid to rainforest.
  4. Most species lay eggs in water bodies which hatch into tadpole larvae but for the genus Nectophrynoides, the eggs hatch directly into miniature toads.
  5. They are toothless with warty in appearance.
  6. They possess a pair of parotoid glands which are situated on the back of their heads.
  7. The male possesses Bidder`s organ.
  8. They have short legs.

Examples: Bufoides meghalayanus, Duttaphrynus melanostictus, Barbarophryne brongersmai, etc.

image of Duttaphrynus melanostictus

Duttaphrynus melanostictus

Family-8: Brachycephalidae

  1. They are commonly known as Robber Frogs, Three-Toed Toadlets.
  2. The family Brachycephalidae contains 74 species in 2 genera.
  3. They inhabit leaf litter in tropical rainforests but some are arboreal.
  4. Direct development occurs.
  5. They are usually diurnal.
  6. Aquatic tadpoles are most probably absent.
  7. Bidder's organ is absent.

Examples: Brachycephalus actaeus, Brachycephalus alipioi , Ischnocnema abdita, Ischnocnema epipeda, etc.

Family-9: Hylidae

  1. They are commonly called treefrogs, leaf frogs.
  2. The family Hylidae contains 1003 species in 53 genera.
  3. Most species are arboreal, some are terrestrial, aquatic or semi-fossorial.
  4. They lay eggs in ponds, on leaves or in wetlands and marches, or treeholes.
  5. Eggs hatch into tadpole larvae.
  6. They are distributed worldwide but many species are found in the North, Central, and South America as well as Eurasia and Australo-Papuan region.

Examples: Hyla arborea, Hyloscirtus albopunctulatus, Argenteohyla siemersi

Family-10: Ranidae

  1. They are also known as true frogs.
  2. The family Ranidae contains 410 species in 25 genera.
  3. They are distributed in North America, Africanorthern South America, Europe,   and Asia.
  4. They have smooth and moist-skin.
  5. The legs are large and powerful with extensively webbed feet.
  6. They are aquatic or live close to water.
  7. The upper jaw possesses teeth.
  8. The body has smooth slimy skin.
  9. They lay their eggs in the water and eggs hatch and go through a tadpole stage.
  10. They have usually a distinct visible tympanum.

Examples: Rana amurensis, Hoplobatrachus tigerinus, Batrachylodes elegans, Amietia amieti, etc.

image of Hoplobatrachus tigerinus

Hoplobatrachus tigerinus

Family-11: Rachophoridae (Polypedatidae)

  1. They are commonly called shrub frogs, moss frogs or bush frogs.
  2. The family Rachophoridae contains 200 species in 10 genera.
  3. Both fore and hind limbs have highly webbed feet.
  4. Fingers and toes are provided with adhesive disc-like pads.
  5. The body size ranges from 1.5 to 12 cm (0.59 to 4.72 inches) in length.
  6. They occur in Africa, India,Sri Lanka, Japan,China, Philippines,  Greater Sundas, and Sulawesi.

Examples: Liuixalus calcarius, Nyctixalus margaritifer, Theloderma andersoni, Rhacophorus lateralis, etc.

image of Rhacophorus lateralis

Rhacophorus lateralis

Family-12: Brevicipitudae

  1. They are commonly Called Rain Frogs, found in eastern and southern Africa.
  2. The family Brevicipitidae contains 35 species in 5 genera.
  3. They inhabit forests and desert.
  4. They are terrestrial and fossorial.
  5. Adult frogs spend extended periods of time in soil or leaf litter.
  6. The head is extremely short.
  7. Development is direct in which fully metamorphosed young hatch directly from eggs.
  8. They lay small clutches of 13 to 56 fairly large eggs with 4–8 mm diameter.

Examples: Balebreviceps hillmani, Breviceps acutirostris, Callulina dawida , etc.

Difference between Amphibia and Reptilia

Difference between Amphibia and Reptilia are stated in the following table:

Amphibia

Reptilia

Amphibians are cold-blooded animals which live on land or in water.

Reptiles are also cold-blooded animals. Some live on land and some other live on water.

The body is covered with smooth, moist and highly porous skin with rich in glands.

The body is covered with dry and hard skin with no glands.

The body does not contain any scales. ​

Bony epidernal scales covers the body.

Skull is articulated with the atlas by two occiptal condyles.

Skull is attached with single median occipital condyle.

They have three chambered heart

with two auricles and one ventricle.

Reptiles also have a three-chambered heart, but their ventricle is further divided through a septum.

Generally, fertilization is external.

Fertilization is internal. 

They lay their eggs in water which are covered with gel.

Reptiles lay their eggs on land which have a hard protective covering.

Foot is webbed which help them in swimming and jumping.

Most of them have four limbs which  help them in swimming and, running but  snakes do not have limbs and they crawl.

They perform respiration through gills or from the lungs.

Reptiles perform respiration only through lungs.

They are oviparous and they lay eggs covered with gel.

Some reptiles are oviparous, while some are viviparous. In this case, if they lay eggs which are covered with a hard protective covering.

Some amphibians such as a tadpole larvae have lateral line sensory organ which  sense water pressure changes to locate prey.

Some reptiles have additional sense organ, known as  vomeronasal organ or  Jacobson's organ which is  located on the roof of the mouth. 

Examples:  Toads, frogs salamanders, and newts, etc.

Examples:  Crocodiles, Alligators, gavials, lizards, snakes, tortoises, turtles, etc.

Concluding Remarks

The name “amphibian” is derived from the Greek word amphibios which means “living a dual life”. There are about 8100 known living amphibians, which play an important role in ecosystem to maintain many food chains. They are herbivorous to omnivorous and eat various animals as food items. They also act as the best biological pest controllers. Besides these, they are the good food source of humans. At present, the population of amphibians are decreasing worldwide due to various activities like habitat destruction, climate change, chemical contamination, pollution and diseases, physical environment changes, etc. To protect them, we should take proper conservation measures from their extinction near the future.

Aves: Characteristics, Classification and Examples

Aves is a class of vertebrates that comprises the birds' species. Birds are bipedal, feathered, and endothermic egg-laying animals. They are found worldwide, and their size ranges from 5 cm (bee hummingbird) to 2.75 m (ostrich). Among the tetrapod classes, birds constitute the largest number of species. There are about 10,000 living modern bird species in the world that occupy nearly all habitats on Earth.

Characteristic Features of Class Aves

  1. The body of the most bird is spindle-shaped, and it is covered with different types of unique structures, feathers for the most part.
  2. Forelimbs are modified as wings for flight, and the posterior hind limbs are adapted for walking, perching, wading, or swimming.
  3. Only legs are covered with scales, usually with four toes on each foot.
  4. The birds' bones are fully ossified and pneumatic or hollow inside, which lower the overall weight of the body.
  5. Uropygial or oil gland is present in the tail region.
  6. The mouth is wide, and jaws are covered by horny sheaths that form strong beaks.
  7. Teeth are not present in the mouth. In this case, food is swallowed unmasticated.
  8. The alimentary canal leads to the cloaca. Alimentary canal often contains additional chambers like crop and gizzard. In this case, the crop stores and softens food while the gizzard is muscular to crush and stir up the softened food.
  9. Some bird species, such as pigeon, keep stone in the gizzard to effectively crush grains and seeds.
  10. Birds are adapted to various modes of feeding due to the modified structures of beak: fruit-scooping, seed-crushing, fish-tearing, wood-chiseling, nectar-sipping, grain-pickling, etc.
  11. The skin is thin, loose, and dry with flight muscle in the thorax; the sweat gland is absent.
  12. The head is small and round with a relatively long, flexible, and movable neck.
  13. They have no urinary bladder.
  14. They have a four-chambered heart with two ventricles and two atria.
  15. The respiratory system can perform double respiration. In this case, air sacs are connected to the lungs, which ensure supplement respiration.
  16. They have small, elastic type lung, which is affixed in the dorsal wall of the thorax and give rise to some air-sacs to increase its efficiency.
  17. The kidney is the excretory organ, which is metanephric, urine is semi-solid.
  18. They have relatively large-sized eyes which powerful with a specialized structure known as pectin.
  19. Birds perform internal fertilization.
  20. They are oviparous, and the matured female lay eggs with a large amount of yolk (telolacithal).
  21. Development is direct, and four embryonic membranes such as amnion, chorion, allantoin, and yolk sac are formed.
image of Aves Classification

At a glance of Aves Classification

Details classification of Class Aves with distinguishing characteristics and examples are described below:

Subclass-1: Archiornithes 

[Gk. Archios = ancient + ornithos = bird]

  1. They were the most primitive and extinct fossil birds of the Jurassic period.
  2. The jaws did not bear teeth.
  3. Archiornithes had a long feathered tail.
  4. They had a reptile-like and elongated body.
  5. Forelimb had three clawed digits,
  6. They had a small brain and eyes.
  7. They had non-pneumatic bones and were capable less specialized for flight.
  8. They had a well-developed beak.

Subclass Archiornithes includes the following order:

Order-1:  Archaeopterygiformes

  1. The tail was long with the distal tapering end.
  2. The forelimbs had remiges with three clawed digits.
  3. Head was large with proportionately large eyes.
  4. They had strong jaws with enameled crowned teeth.
  5. Cerebral hemispheres were smooth, long, and narrow with small cerebellum.

Examples: Archaeopteryx lithographica, Archaeornis siemensi.

image of Archaeopteryx lithographica

Archaeopteryx lithographica

Subclass-2: Neornithes

All the modern birds belong to the subclass Neornithes. This subclass contains about 10,000 known living birds' species throughout the world. The representatives of this subclass first appeared in the Cretaceous period of the Mesozoic Era. This subclass also includes a few extinct birds.

  1. They have a well-developed sternum, which is usually keeled or carinate.
  2. They do not bear long tail with no teeth on both jaws. In this case, teeth are replaced by horny rhamphotheca over the bill, but extinct forms had teeth.
  3. The forelimbs become modified to wings.

The subclass Neornithes is further divided into the following four superorders:

  • Superorder-1: Odontognathae
  • Superorder-2: Palaeognathae
  • Superorder-3: Impennae and
  • Superorder-4: Neognathae

Superorder-1: Odontognathae

[Gk. Odontos = teeth + gnathos = jaw] 

  1. They were the New World toothed birds. They were found in the Upper Cretaceous period of the Mesozoic Era (100.5 - 66 MYA).
  2. They had short tails with a plowshare-shaped pygostyle.
  3. They had a well-developed carina for flight muscle.
  4. Both jaws had teeth.
  5. They were flightless birds but were specialized for swimming.
  6. They had intramandibular articulation.
  7. Sternum did not bear keel and wings had vestigial humorous only.

Superorder Odontognathae is divided into the following orders:

Order- 1: Hesperornithiformes (extinct)

  1. They were extinct aquatic birds and inhabited in both freshwater and marine habitats in the Northern Hemisphere.
  2. They were flightless predatory divers with strong swimming behavior.
  3. They reached a maximum length of over 1.5 meters.
  4. They had a long neck with heterocoelous vertebrae.
  5. Forelimbs had vestigial humerus only.
  6. Both jaws had pointed teeth, but the premaxilla did not bear teeth.
  7. The hind limbs brought webbed feet.

Examples: Parahesperornis,  Hesperornis,   Enaliornis, Baptornis, Neogaeornis, and Potamornis.

image of Hesperornis

Hesperornis

Order- 2: Ichthyornithiformes (extinct)

  1. The representatives of Order  Ichthyornithiformes were small-sized marine flying birds, of Upper Cre­taceous of North America.
  2. They found throughout the late Cretaceous period (80–65 million years ago) of North America.
  3. They became extinct at the Cretaceous–Paleogene boundary.
  4. They had amphicoelous vertebrae in the neck region.
  5. They had a well-developed keel in the sternum with fused clavicles.

Examples: Ichthyornis, Apatornis

image of Ichthyornis

Ichthyornis,

Superorder-2: Palaeognathae

  1. Superorder Palaeognathae contains 47 species, of which, three cassowaries (Casuarius), five kiwis (Apteryx), 1 emu (Dromaius), two ostrich (Struthio) and two species of rheas (Rhea).
  2. Most of the birds are flightless. In this case, some anatomical features are associated with flightlessness. These include reduced keel on the sternum, reduced wing bones, etc.
  3. All species of tinamous can fly, but they are very terrestrial.
  4. During reproduction, the male provides parental care.
  5. The males have an erectile penis and the females with the clitoris.
  6. They show unusual mating system such as polygynandry/promiscuity.
  7. They have primitive types of feathers that do not bear hooked barbules.
  8. The rectrices or flight feathers are absent or irregularly arranged.
  9. They have small or poorly developed pygostyle.
  10. Wings are absent; if present, they are vestigial or reduced in size. 
  11. The flat, raft-like sternum is present.

The superorder Palaeognathae includes the following seven orders (of which two are extinct).

Order- 1:  Struthioniformes

[Gk. Struthio = Ostrich + form]

  1. They are the largest flightless, running birds found in Africa and Arabia.
  2. Struthioniforms can reach up to 210 cm in length and 170 kg in weight.
  3. They inhabit arid lands forming a flock of 3-20 birds.
  4. The members of Struthioniformes bear degenerated breast muscles with no keel of the sternum.
  5. Legs are strong and the leg bones without air chambers.
  6. The flight and tail feathers are converted to decorative plumes.
  7. The uropygial gland or preen gland is absent.
  8. All are omnivorous and feed on all types of food.
  9. Wings are small, which usually kept folded during running.
  10. The head, neck, and leg bear feathers sparsely.
  11. Feathers do not contain aftershaft.
  12. Tail feathers are put back by tail coverts.
  13. They have strongly build hind limbs, and each foot bears only two toes.
  14. The pygostyle is absent, and the sternum does not contain keel.
  15. During the breeding season, the female lays up to 30 eggs.

Example:  Common ostrich, or simply ostrich (Struthio camelus)

image of Struthio camelus

Struthio camelus

Order- 2:  Rheiformes

[Gk. Rhea = mother of Zeus + form]​​​​

  1. Rheiformes are large flightless running ratite birds native to South America.
  2. They inhabit groups of a variety of open areas, such as grasslands, savanna, or grassy wetlands.
  3. They can live up to 10.5 years and can reach about 120 cm tall with a weight of 23-25 kg.
  4. During the breeding season, the male builds a nest, and the female lays her eggs in the nests.
  5. The male incubates the eggs for about 40 days.
  6. All members of this order are omnivorous and prefer to eat broad-leafed plants. They also eat seeds, fruit, roots, insects, and small vertebrates.
  7. Each foot bears three front toes, which are webbed at the base.

Examples: Rhea americana, Pteronemia pennata.

image of Rhea americana

Rhea americana,

Order-3: Casuariiformes

  1. Casuariiformes are large, flightless terrestrial birds native to Australia.
  2. This group includes the emus and cassowaries. In this case, the emus can grow up to 1-8 meters in height and 55 kg in weight.
  3. They are large and heavy birds, while the females are usually slightly larger than males.
  4. Legs are long and robust while the head is relatively small, and the neck is long.
  5. The plumage is usually brown in color while the head is naked, and the neck is blue in color in emus and orange/red in cassowaries.
  6. They have no differentiated tails or tail feathers.
  7. Hair-like feathers with no barbules.
  8. The foot is three-toed of which, the middle toe on both legs bear an elongated and dagger-like claw.
  9. The wings are modified into five hollow spines.
  10. The birds do not build a nest, and the female lays her eggs into depression in the grass.
  11. The male incubates the eggs as well as care for the young hatchlings.
  12. The baby birds reach maturity within two years.
  13. They are aggressive birds and prefer to live in tropical rainforests. In this case, emus inhabit in different conditions, from forest to grasslands.
  14. All are herbivorous and prefer to feed on fruit, seeds, and grasses.

Examples: Dromaeus novaehollandiae (Emu), Southern cassowary (Casuarius casuarius).

image of Dromaeus novaehollandiae

Dromaeus novaehollandiae

Order- 4: Apterygiformes

  1. Apterygiformes are flightless birds endemic to New Zealand.
  2. The birds are pink, brown, and grey in colors.
  3. The body is small pear-shaped with vestigial wings and small eyes. In this case, wings are about 4-5 cm long, and each wing has a claw that hidden in the plumage.
  4. They have robust legs and feet. In this case, each leg contains four-clawed toes.
  5. The beak is long, flexible, which is downward curved at the end with a thick and horny tongue. In this case, the beak also contains nostrils at the tip.
  6. The plumages are feathery, hair-like with a soft base that does not contain after shafts.  In this case, juvenile bears softer feathers than the adult.
  7. They prefer to live in rainforests, but they can also be found in grasslands, shrubs, and pine forests.
  8. Apterygiformes are omnivorous and prefer to feed on earthworms, beetles,  larvae, fruits, and leaves.
  9. They are monogamous birds: during the breeding season, they make burrows into the soil or use natural holes and caves as nests for laying eggs.
  10. The matured female lays one or two eggs, and the female incubates the eggs until hatching. In this case, both males and females take care for their hatchlings.

Examples: Southern Brown Kiwi (Apteryx australis), North Island Brown Kiwi (Apterix mantelli), Great Spotted Kiwi (Apteryx haastii), Okarito Kiwi (Apterix rowi). Little Spotted Kiwi (Apteryx owenii), etc.

image of Apteryx australis

Southern Brown Kiwi (Apteryx australis)

Order- 5: Dinornithiformes (extinct)

  1. Dinornithiformes were flightless running birds, commonly called Moa, endemic to New Zealand. They are now extinct.
  2. They reached about 3.6 meters in height and 230 kg in weight.
  3. The body was covered by feathers with large after shafts and without barbicels.
  4. The beak was short, and the hind limbs had four toes.
  5. Sternum was un-keeled.

Examples: Dinornis robustus and Dinornis novaezelandiae

image of Dinornis robustus

Dinornis robustus

Order- 6:  Aepyornithiformes (Extinct)

  1. Aepyornithiformes are the extinct large to enormous flightless birds, also known as giant flightless Madagascar elephant birds.
  2. They reached up to 9.8 feet in height and 500 kg in weight.
  3. They had relatively tiny wings and stout, powerful legs with four toes.
  4. They became extinct since at least the 17th century due to human activities.
  5. Their egg length was up to 34 cm and weight 1o kg with volume up to 2 liters. It was 160 times larger than a chicken egg.

Examples: Aepyornis maximus, A. hildebrandti, A. medius, A. gracilis,  Mullerornis agilis, M. rudis, M. betsilei, etc....

image of Aepyornis maximus

Aepyornis maximus

Order-7: Tinamiformes

  1. The order Tinamiformes contains 47 species in nine genera under the family,Tinamidae; found in Southern Mexico and Central and South America.
  2. They are cursorial birds commonly known as Tinamon, which can fly over a short distance. They are also able to walk and run rapidly.
  3. They inhabit a wide variety of habitats, such as tropical rain forests, scrubby woodlands, forest edges, arid or semi-arid grasslands, etc.
  4. The body is heavy chicken-like, and the coloration of plumage ranges from light or dark brown to gray. Some have dark-spotted or barred patterns. 
  5. The neck is long slender with a small head and thin decurved bill.
  6. The body reaches up to 50 cm in length and 2kg in weight.
  7. The leg is medium long with short wings and tail.
  8. The legs bear three short toes and one backward pointed toe.
  9. The skeleton is pneumatic with a carinate sternum.
  10. The uropygial gland is small and tufted.
  11. All birds are omnivorous and prefer to feed on seeds, fruits, roots, insects, termites, spiders, ticks. Some also feed on small vertebrates like lizards, mice, frogs, etc.
  12. During the breeding season, they build a nest in the ground near the base of grasses or trees.
  13. The matured females lay 3-4 eggs, and the male incubates the eggs for 17-21 days.
  14. After hatchings, the young, parents provide care for one to two months..

Examples: Barred tinamou (Crypturellus casiquiare),  Bartlett's tinamou ( Crypturellus bartletti).

image of Crypturellus bartletti

Bartlett's tinamou ( Crypturellus bartletti).

Superorder-3: Impennae

They are flightless aquatic birds. Their forelimbs are modified into paddles, which are used for both swimming and flight. This superorder includes only one order.

Order: Spheniseiformes

[Gk. Spheniscus = wedge + form]

  1. Spheniseiformes are flightless aquatic birds, which belong to the family, Spheniscidae, commonly known as penguin, found southern part of South America, South Africa Australia, Antarctic regions and Galapagos Islands.
  2. The body is medium to large which can grow up to 115 cm in height and 40 kg in weight.
  3. The plumage of adult birds is blue-black or gray dorsally and white ventrally.
  4. They have either entirely brown–gray or white ventrally chicks.
  5. The feathers are small, scale-like, and continuous.
  6. Long and often laterally compressed bills are present. 
  7. The skeleton is poorly pneumatized with the carinate sternum.
  8. The wings are modified to form flippers.
  9. The legs are short, which are placed far posterior on the body.
  10. They have palmate feet, which are strongly webbed with pointing toes.
  11. Hind limbs are modified for swimming.
  12. The oil gland is present, which is tufted. 
  13. They are monogamous, and the mature female lays only one egg at a time.
  14. All birds are carnivorous and mainly feed on fishes, crustaceans, squids, etc.

Examples: Emperor penguin (Aptenodytes forsteri), Adélie penguin (Pygoscelis adeliae), Crested penguin (Eudyptes calauina), Little penguin (Eudyptula minor),  Magellanic penguin (Spheniscus magellanicus), etc.

image of Emperor penguin

Emperor penguin (Aptenodytes forsteri)

Superorder-4: Neognathae

The word "Nognathe" is derived from Greek 'neo' meaning new and 'gnathos' meaning jaw. This superorder includes all modern living birds with nearly 10,000 species.

  1. Neognathae have well-developed wings which are fully adapted for flight.
  2. The beak does not contain any teeth.
  3. The forelimbs have fused metacarpals with an elongated third finger.
  4. Pygostyle is absent, and the tail is composed of 5-6 vertebrae.
  5. The sternum is well-developed with the keel.
  6. Rectrices are organized in a semicircular manner, which helps in flight.
  7. They have a neognathous type skull where the palatines are protruded poste­riorly and come in contact with the base of the cranium.

Superorder-Neognathae is divided into the following orders:

Order-1: Gaviiformes (Loons)

  1. The order Gaviiformes contains five living species, and all are placed in the genus Gavia under one family, Gaviidae.
  2. They are medium to large-sized aquatic birds.
  3. They are also known as Piscivorous sea or lake-birds found in North America, Europe, and the Arctic.
  4. They are adapted for diving and swimming.
  5. They can also be able to fly.
  6. The legs are short with webbed toes.
  7. The bill is sharp and dragger-like.
  8. Their size ranges from 20.8–35.8 in (53–91 cm) with 1.0–6.4 kg in weight.
  9. The males are slightly larger than the females.
  10. They inhabit forested and tundra lakes and ponds, but in the winter season, they inhabit at sea and large reservoirs.
  11. During the breeding season, plumage becomes boldly patterned primarily with black, white, and gray, while the non-breeding plumages are drab gray-brown and white.
  12. The eyes have a brilliant red iris.
  13. All birds are carnivorous and mainly feed on fish and crustaceans.
  14. The neck is long with short wings.
  15. The matured female lays eggs in a nest among piles of vegetation.

Examples: Gavia arctica and G. stellata 

image of Gavia arctica

Gavia arctica

Order-2: Podicipediformes (Grebes)

  1. All the members of this order are also known as grebes.
  2. This order contains two species in 6 extant genera under one family (Podicipedidae).
  3. They are freshwater diving birds, distributed worldwide. 
  4. The body is small to medium-large, which can grow up to 78 cm (31 inches) in length.
  5. They have little tails with degenerated feathers and silky plumage.
  6. They are excellent divers and swimmers.
  7. They dwell in ponds, lakes, and rivers.
  8. The bills are moderately long, while wings are short.
  9. The eyes are red, yellow, or brown.
  10. The legs bear lobed toes. 
  11. They are carnivorous and feed on fish, crustaceans, aquatic insects, mollusks, and small vertebrates.

Examples:  Great crested grebe (Podiceps cristatus), Western grebe (Aechmophorus occidentalis), Pied-billed grebe (Podilymbus podiceps), etc.

Order-3: Procellariiformes (Tube-nosed seabirds)

  1. The order Procellariiformes contains 117 species under four families, including the birds' groups like albatrosses, shearwaters, and petrels. 
  2. They are also known as tube-nosed seabirds distributed throughout the world.
  3. The body size can reach a length of 13–200 cm (5.1–79 inches) with a wingspan of more than 3 meters (10 feet).
  4. The beak is long hooked at the tip.
  5. The wings are long, narrow, and pointed. 
  6. The foot is webbed with a strong hind claw.
  7. The tail is short and rounded.
  8. The plumages are oily and compact.
  9. Hind toe is vestigial or none.
  10. The plumage is compact and oily.
  11. During the breeding season, they come to land only and build-up nest in holes.

Examples: Leach's storm petrel (Oceanodroma leucorhoa), Audubon's shearwater (Puffinus lherminieri), common diving petrel (Pelecanoides urinatrix), slender-billed prion (Pachyptila belcheri), etc.

The order Procellariiformes  includes the following four families:

  1. Diomedeidae
  2. Procellariidae
  3. Hydrobatidae
  4. Pelecanoididae

Order-4: Pelecaniformes (Waterbirds)

[Gr. Pelikan = Pelican + form]

  1. The order Pelecaniformes contains 66 species under six families, distributed worldwide, including the birds' group like boobies, cormorants,  tropicbirds, gannets,  and frigate birds.
  2. The body is medium-sized and large, which varies from 19–74 inches (48–188 cm) in length.
  3. The leg is short with large webbed toes.
  4. The body is brown, black, or white in colors or a combination of those colors.
  5. The bill is hooked or straight with sharply pointed.
  6. The birds are carnivorous and mainly feed on fish. Some also take squid, crustaceans, amphibians, and reptiles, etc.
  7. They inhabit marine and freshwater habitats throughout the world.
  8. Most species of this order bear a bare gular pouch or throat pouch, which is situated between their lower jaws.
  9. They also bear a comb-like pectinate nail on their longest toe, which is used for brushing out and separate their feathers. 
  10. The birds are monogamous, and during the breeding season, they build a nest where the mature females lay eggs. Both the female and male incubate the eggs and care for the babies.

Examples: Dalmatian pelican (Pelecanus crispus),  Pygmy cormorant (Phalacrocorax pygmaeus), Red-footed Booby (Sula sula), Snakebird (Anhinga anhinga),   Red-tailed tropicbird (Phaethon rubricauda), etc.

image of Pelecanus crispus

Dalmatian pelican (Pelecanus crispus)

The order Pelecaniformes includes the following six families:

  1. Phaethontidae
  2. Fregatidae
  3. Sulidae
  4. Phalacrocoracidae
  5. Anhingidae
  6. Pelecanidae

Order-5: Ciconiiformes (herons, storks, Egrets, Flamingos and their allies)

[L. Ciconia = stork + form]

  1. The order Ciconiiformes includes 120 species under five families, found worldwide in tropical and subtropical areas, but storks and herons can also be found in more temperate regions.
  2. They are long-legged wading birds with medium to the large-sized stocky body, which reach a length of 9.7–60 inches (25–152 cm).
  3. They have a long slender, flexible neck with long straight, sharp, and dagger-like bills. In this case, new world vultures have bills with serrated edges for eating meat.
  4. Middle and outer toes of the feet are webbed at the base.
  5. The wings are large, with a usually short tail.
  6. The order Ciconiiformes includes both sedentary and migratory species. In this case, most of the birds form roots on trees where they return each year.
  7. Their food consists of fish, other aquatic animals, small mammals, and rarely seeds and fruits.
  8. During the breeding season, herons use their ornamental plumes for courtship.
  9. Most of the species build nests using sticks on trees, but only vultures do not build nests; they lay eggs in caves or under bushes.
  10. Both the male and female take care of the young.
  11. Most of the species of Ciconiiformes have combined color plumage, which may be grey, white, and black.
  12. Most of the representatives of this order settle in wetlands or shorelines of large bodies of water for searching their food
  13. Most species of the order are found in tropical and subtropical areas, though species such as storks and herons can be found in more temperate regions.
  14. The representatives of the order (except vultures) mostly settle in wetlands, sometimes search for food near shorelines of large bodies of water.

Examples: Great blue heron (Ardea herodias), Snowy egret (Egretta thula), Cattle egret(Bubulcus ibis), Shoebill (Balaeniceps rexi), Marabou stork (Leptoptilos crumeniferus), Jabiru (Jabiru mycteria), White Ibis(Eudocimus albus), Black vulture (Coragyps atratus), California condor (Gymnogyps californianus), Turkey vulture(Cathartes aura), etc.

image of Ardea herodias

Great blue heron (Ardea herodias)

The order Ciconiiformes includes the following five families:

  1. Ardeidae
  2. Balaenicipitidae
  3. Scopidae
  4. Threskiornithidae
  5. Ciconiidae

Order-6: Anseriformes (screamers, waterfowl)

[L. Anser = goose + form]

  1. The order Anseriformes contain about 170 species under three families, namely Anatidae (ducks, geese, swans), Anseranatidae (Magpie Goose), and Anhimidae (screamers).
  2. The representatives of this order are called waterfowl birds because they inhabit near freshwater bodies such as ponds, lakes or other water-resource areas.
  3. They are large water birds having broad, flat bills with comb-like margins which are used for filtering food particles.
  4. The tail is short; wings are usually narrow and pointed. In this case, migratory species bear powerful wings that are adapted for flights long distance.
  5. The legs are short, sturdy having feet usually webbing between the toes, which are adapted for walking or swimming.
  6. The colors of the birds vary from black, grey, and brown to brighter coloring.
  7. The birds have medium to long neck.
  8. The food of Anseriformes consist of plants and their parts, such as leaves or seeds, insects, planktons or mollusks, etc
  9. Most of the Anseriformes are monogamous; during the breeding season, most species form the same pair from year to year. The matured ducks and swans females lay several eggs. 
  10. The parents care for their young, and they watch over their feeding, flying, and swimming.
  11. The young hatchlings are well-developed and are usually able to see and walk almost immediately.

Examples: The mallard (Anas platyrhynchos), Coscoroba swan (Coscoroba coscoroba) , Canada geese (Branta canadensis) , Common eider (Somateria mollissima), , Muscovy duck (Cairina moschata), Steller's eider (Polysticta stelleri), White-headed Duck (Oxyura leucocephala),etc.

image of Anas platyrhynchos

The mallard (Anas platyrhynchos)

Order -7:  Falconiformes  (diurnal birds of prey)

[L. Falco = falcon + form]

  1. The order Falconiformes contains 309 species of birds under five families. The representatives of the orders include the bird groups like falcons, hawks,  eagles, the secretary bird, vultures, and condors.
  2. The maximum length of the bids ranges from 14–150 cm (5.5–59 inches), having wingspan more than 10 feet (3 meters).
  3. The beak is short with longer upper mandible that is hooked at the tip for tearing flesh.
  4. Most of the birds of falconiformes have strong legs, which bear strong and powerful feet with hooked claws.
  5. They have well-developed sight and hearing with brown eyes (except eagles, who have golden eyes). In this case, eyes are laterally placed. 
  6. Their food consists of living vertebrates such as fish and insects.
  7. Most bird species are monogamous. The matured females lay eggs and incubate it. The males take care and feed the females during the incubation period.

Examples: Peregrine falcon(Falco peregrines), Fox Kestrel (Falco alopex), Merlin (Falco columbarius),Common kestrel (Falco tinnunculus), Laughing falcon (Herpetotheres cachinnans), Lined forest falcon (Micrastur gilvicollis), Crested Caracara (Caracara cheriway), Spot-winged falconet (Spiziapteryx circumcincta), Pygmy falcon (Polihierax semitorquatus).

image of Peregrine falcon(Falco peregrines)

Peregrine falcon(Falco peregrines)

The order Falconiformes includes the following five families:

  1. Cathartidae,
  2. Pandionidae,
  3. Accipitridae,
  4. Sagittariidae,
  5. Falconidae

Order- 8: Galliformes (chicken-like birds)

[L. Callus = Cock + form]

  1. The Order Galliformes contains about 290 species under four families. The representatives of this order include birds groups like Game birds, Megapods, Hoatzins, Patridge, Turkey, Quail, Fowls, Guinea Fowl, Pheasants, Peacocks, guans and curassows, found nearly worldwide.
  2. The legs are stout, and un-feathered with strong clawed for scratching soil for searching food. In this case, three toes are anteriorly directed.
  3. Wings are short, rounded, and the feathers with long aftershafts.
  4. The length of the body ranges from 5.9 inches to more than 79 inches (15 to more than 200 cm).
  5. The feet have short, strong, and blunt claws.
  6. The members of Galliformes have short, strong, and arched beak suitable for picking up grains or seeds.
  7. Many representatives of the Galliformes have ornamental tails and bright crests.
  8. They have compact bodies with small-sized head.
  9. Males are aggressive polygamous and build mounds for incubating their eggs.

Examples: Great Curassow (Crax rubra), Rock ptarmigan (Lagopus muta), Rock partridge (Alectoris graeca), Common Quail (Cotumix cotumix),  Common pheasant (Phasianus colchicus),  Wild turkey (Meleagris gallopavo) , Hoatzin (Opisthocomus hoazin), etc.

image of Crax rubra

Great Curassow (Crax rubra)

The Order Galliformes  includes the following four families:

  1. Cracidae,
  2. Megapodiidae,
  3. Numididae,
  4. Phasianidae.

Order- 9: Gruiformes (cranes and their allies)

  1. The order Gruiformes contains about 210 species under11 families, found worldwide.
  2. Most of the birds have grey, white, or brown colors.
  3. The body length ranges from 4.7–70 inches (12–176 cm).
  4. Many members of the Gruiformes have long and strong legs with long, slender bills.
  5. The wings are long with rounded edges.
  6. Most of the birds feed on fish, mollusks, and reptiles.
  7. The power of fight is weak, and toes are slightly webbed.
  8. They are known for special mating rituals. They built a nest on the ground.

Examples: Common crane (Grus grus), Water rail (Rallus aquaticus),  Eurasian or common coot (Fulica atra), Common moorhen (Gallinula chloropus),  Kagu or cagou (Rhynochetos jubatus) , Common Buttonquail(Turnix sylvaticus), etc.

image of Common crane-(Grus grus)

Common crane (Grus grus)

The order Gruiformes includes the following 11 families:

  1. Rallidae,
  2. Heliornithidae,
  3. Rhynochetidae,
  4. Eurypygidae,
  5. Mesoenatidae,
  6. Turnicidae,
  7. Gruidae,
  8. Aramidae,
  9. Psophiidae,
  10. Cariamidae,
  11. Otididae

Order -10: Diatrymiformes (Extinct)

  1. Diatrymiformes were large flightless birds of Europe and North America.
  2. They have been found in the Eocene period(55 to 65 MYA).
  3. They had massive head, neck, and beak.
  4. The birds were over two meters tall with large skulls.
  5. They weighed about 100 kg.

Example: Diatryma(Gastornis).

image of Diatryma

Diatryma 

Order-11: Charadriiformes  (gulls, sandpipers, auks, and their allies)

[L. Charadrius = Genus of Plovers + form]

  1. The order Charadriiformes contains 370 species under 17 families, including the bird groups like plovers, jacanas, stilts, avocets, thickknees, terns, and murres.
  2. The representatives of Charadriiformes have a cosmopolitan distribution.
  3. They inhabit near water; some live inshore, some in aquatic leaves while some are aquatic.
  4. They have more or less longer legs with only three toes. In this case, toes are usually webbed, at least at the base.
  5. The members of this order have firm and dense plumage.
  6. The length of the body ranges from 4.7–30.7 inches (12–78 cm).
  7. Shorebirds search their food in mud, sand, or shallow waters.
  8. All birds are usually carnivorous and feed on fish, invertebrates, or other small animals in mud or water. 
  9. Beak is variously modified, hallux small or absent.

Examples: Kentish plover (Charadrius alexandrinus), Wattled jacana( Jacana jacana), Australian Painted-snipe (Rostratula australis),  Eurasian oystercatcher (Haematopus ostralegus),  Northern lapwings (Vanellus vanellus),   Whimbrel (Numenius phaeopus) ,  Collared pratincole (Glareola pratincola), Western gulls (Larus occidentalis) , Atlantic puffin (Fratercula arctica),  etc.

image of Charadrius alexandrinus

Kentish plover (Charadrius alexandrinus)

Order-12: Columbiformes: (pigeons and doves)

[L. Columbia = a dove + form]

  1. The order Columbiformes contains over 300 species under one family(Columbidae), found worldwide.
  2. The length of the body ranges from 5.9–47.2 inches (15–120 cm).
  3. They are fast-flying birds having slender and short bills. 
  4. The wings are long, pointed, which help the birds to make a sustained flight at a great speed.
  5. The base of the beak is covered by soft skin, having longi­tudinal slit-like nostrils called cere.
  6. The head and neck are small and compact.
  7. The legs are small in size, with all the toes lie down in the same plane.
  8. The members of this order bear large crop which can produce pigeon milk during the breeding season.
  9. They are monogamous, and the matured female lays 2-3 eggs.
  10. Both males and females incubate the eggs, and the female nourishes the young with the help of 'pigeon milk' produced by both sexes.
  11. They are herbivorous and feed on seeds and fruit.

Examples: Pin-tailed sandgrouse (Pterocles alchata),   Eurasian collared dove (Streptopelia decaocto), Rock pigeons (Columba livia), Little green pigeon (Treron olax),  Tooth-billed pigeon (Didunculus strigirostris), etc.

image of Pterocles alchata

 Pin-tailed sandgrouse (Pterocles alchata)

Order-13: Psittaciformes (parrots, lorikeets, cockatoos, kea, and kakapo)

[L. Psittacus = Parrot + form]

  1. The order Psittaciformes contains 369 species under 2 families (Psittacidae, Cacatuidae).
  2. Psittaciformes are omnivorous, and they feed both meat and vegetation. Their food consists of flowers, nuts, fruit, seeds, buds, and insects, etc.
  3. The Psittaciformes have brightly colored plumage. Most of the birds bear green feathers, and many have blue, red, and yellow colors.
  4. They have a sturdy body, and the length of the body ranges from 3.2–39 inches (8–100 cm). Red-breasted pygmy parrot reaches up to 3.3-foot (1-meter).
  5. The head is large with a short neck and curved beak.  In this case, the hooked and curved beaks are used to crack nuts and branches of grab.
  6. The foot is stout with four toes; among them, two are directed forwards, and the other two are directed toward the rear.
  7. Most of the parrot species reach sexual maturity at around twelve months of age.
  8. The Psittaciformes are strictly monoga­mous and build a nest in the trees hollows and termite mounds.
  9. The wings are broad and pointed with a highly variable tail in both shape and length. Some species have a short and rounded tail, while other species have an extremely long and pointed tail.
  10. The parents take care of their babies till they attain maturity.

Examples: Blue-and-yellow macaw (Ara ararauna), Blue-eyed cockatoo (Cacatua ophthalmica), Grey parrot (Psittacus erithacus),  Carolina parakeet (Conuropsis carolinensis) ,  Yellow-collared lovebird(Agapornis personatus), Rose-ringed parakeet (Psittacula krameri),  Thick-billed parrot (Rhynchopsitta pachyrhyncha), etc.

image of Ara ararauna

Blue-and-yellow macaw (Ara ararauna)

Order-14: Cuculiformes (cuckoos and their allies)

[L. Cuculus = Cuckoo + form]

  1. The order Cuculiformes contains 141 species under two families(Cuculidae, Opisthocomidae), including the birds' groups like anis, roadrunners, and the hoatzin, found worldwide in temperate and tropical regions.
  2. The size of the body ranges from 15 cm (6 inches) to nearly 90 cm (about 3 feet) in length.  In this case, the large ground cuckoos (Carpococcyx) reaches a 15 cm (6 inches) while the larger species of coucals (Centropus) reaches a 90 cm (about 3 feet) in length.
  3. Most of the members have fairly loose-webbed feathers with varying colors: black, to brilliant, browns, grays, iridescent greens, olive, purples, and bright yellow.
  4. The beak of the Cuculiformes is of moderate length with slightly curved.
  5. The beak is of moderate length and often slightly downcurved.
  6. The wings are pointed, and the tails are long with graduated feathers.
  7. The leg is strong, and the directed backward outer toes are present on their feet. In this case, toes are two in fronts, and two behind.
  8. Many species have parasitic behavior. They lay eggs into the nests of other birds like a crow for incubation and rearing of young.

Examples: Yellow-billed Cuckoo(Coccyzus americanus), Squirrel Cuckoo (Piaya cayana), Greater Roadrunner (Geococcyx californianus), Goliath Coucal (Centropus goliath), Asian Koel (Eudynamys scolopaceus), Guira Cuckoo (Guira guira), Greater Anis(Crotophaga major), etc.

image of Coccyzus americanus

Yellow-billed Cuckoo (Coccyzus americanus)

Order-15: Strigiformes (owls)

[L. Strix = Screech owl + form]

  1. The order Strigiformes contains 180 species in two families(Strigidae and Tytonidae.), including nocturnal birds, the owls found worldwide.
  2. The body size ranges from 4.7–30 inches (12–69 cm) in length.
  3. The birds bear soft-textured plumage and hooked beaks with strong talons.
  4. The head is large and round with a highly flexible neck to look sideways.
  5. Eyes are large and rounded with directed forward; upper eyelid is large.
  6. The beak is short, hooked, and sharp.
  7. Feet contain sharp claws, adapted for grasping.
  8. Ear openings are large often with a flap-like cover
  9. They build a nest in holes of trees or buildings. They lay white eggs in nests.

Examples:  Eurasian eagle-owl (Bubo bubo), Greater sooty owl(Tyto tenebricosa),  Long-eared owl (Asio otus), Northern Pygmy Owl (Claucidium Californicum) , Burrowing Owl (Speotyto cunicularia), Lesser horned owl (Bubo magellanicus), etc.

image of Asio otus

Long-eared owl (Asio otus)

Order-16:Caprimulgiformes (nightjars)

[L. Caprimulgus = goat sucker + form]

  1. The order caprimulgiformes contains 121 species under 5 families including the birds group like frogmouths, potoos, and the oilbird, found worldwide.
  2. The size of the body ranges from 6–24 inches (15–60 cm) in length.
  3. They have soft plumage with small weak feet and a very largemouth.
  4. The bill is short, flexible with a large gape.
  5. Wings are long, and around the nostril, bristles are present.
  6. They inhabit in woods or bush and forage near ground or high in the air, and feeding insects caught in flight at night or dusk due to their nocturnal behavior.
  7. They lay eggs on the ground in a bush.

Examples: Tawny frogmouth (Podargus strigoides), Great potoo (Nyctibius grandis), Common Nighthawks (Chordeiles minor), European nightjar or common nightjar(Caprimulgus europaeus),  Common pauraque (Nyctidromus albicollis), etc.

image of Chordeiles minor

Common Nighthawks (Chordeiles minor)

Order-17: Apodiformes (swifts, hummingbirds)

  1. The order Apodiformes contains approximately 425 species in three families(Apodidae, Hemiprocnidae, and Trochilidae), including the birds' group like the swifts, treeswifts, and the hummingbirds, found worldwide.
  2. They are rapid-flying birds due to their forked tail that is crucial for steering the flight.
  3. Apodiformes feed on small insects and spiders or nectar from the flowers using tubular protrusible tongue and needle-like bill.
  4. The body size is either small or very small, which ranges from 2.5–9.1 inches (6.3–23 cm) in length.
  5. The legs are short with very small feet.
  6. The wings are pointed, and the bills are small and weak in swifts while in hummingbirds, it is slender with a  long tubular tongue.
  7. The swifts have a broad mouth with large eyes.
  8. Predominantly, bright-colored plumage is present in hummingbirds while in swifts, the body is mostly black, grey, or brown in colors.
  9. Both hummingbirds and swifts build cup-like nests, and the matured females lay one or two small eggs in the nests.
  10. The eggs hatch after few days of incubation and produce naked and blind young chicks that develop in their nests for a long time.

Examples: Amethyst Woodstar(Calliphlox amethystine), Andean Emerald ( Agyrtria franciae), Black Inca (Coeligena prunellei). Copper-Tailed Hummingbird (Saucerottia cupreicauda), Magnificent hummingbird ( Eugenes fulgens). Jamaican Mango( Anthracothorax mango), Spot-fronted swift (Cypseloides cherriei), Sooty swift (Cypseloides fumigates), Rotschild's swift (Cypseloides rothschildi), Indian swiftlet(Aerodramus unicolor), etc.

image of Calliphlox amethystine

Amethyst Woodstar (Calliphlox amethystine)

Order-18: Coliiformes (colies, or mouse-birds)

[Gk. Colius = Genus of the mouse bird + form]

  1. The order Coliiformes contains 6 species under 1 family ( Coliidae,)found in Africa, south of the Sahara.
  2. They are commonly known as colies, or mousebirds due to the presence of feathers that resemble the texture of the mouse skin.
  3. The body is covered with soft plumage with long, pointed tails.
  4. The body size ranges from 11–14 inches (29–36 cm) in length and about 45 to 55 grams in weight.
  5. The body is usually grey and brown in color.
  6. The leg is short with four toes, which are directed forward, having sharp claws for climbing on trees.
  7. The bills of the mouse-birds are short and stubby.
  8. They usually bear a crest on the head.
  9. They inhabit forests as well as on trees near shores and in savannas.
  10. The Apodiformes are monogamous/polygynous, and during the breeding season, they make a cup-shaped twig nest in trees.
  11. The matured female lays 2-4 tiny eggs in their nests. Both parents care for their young babies.
  12. The food consists of  mouse-birds fruit,  blossoms, seeds, and other types of vegetation.

Examples: Bar-breasted mousebirds(Colius striatus), Chestnut-backed mousebird (Colius castanotus), White-headed mousebird (Colius leucocephalus), White-backed mousebird (Colius colius), Blue-naped mousebird (Urocolius macrourus), Red-faced mousebird (Urocolius indicus).

image of Colius striatus

Bar-breasted mousebirds(Colius striatus)

Order-19: Trogoniformes (trogons)

[Gk. Trogon = gnawing + form]

  1. The order Trogoniformes contains 39 species in seven genera under 1 family (Trogonidae), including the birds' group like the trogons and quetzals; found in Asia, Africa, and Tropical America except for Australasia.
  2. Trogons inhabit lowland evergreen forest, pine forest, and tropical deciduous forest.
  3. The birds have a medium-sized body with 9.1–16 inches (23–40 cm) in length and 35 and 210 grams in weight.
  4. The body is covered with thin, delicate skin with soft, dense, and brightly plumage. In this case, the upper side of the body, head, breast, and back has a brilliant green with some yellow, blue, or violet while yellow, orange, pink, or carmine colors on the belly.
  5. The neck is short with short, heavy, broad-hooked bills and bristles at the base.
  6. The wings are short and rounded with long, broadly squared tails.
  7. The trogons have small and weak legs and feet.
  8. The tail is long and stiff, which supports against the vertical surface at the time of digging.

Examples: Narina trogon (Apaloderma narina),  Red-naped trogon (Harpactes kasumba), Cuban trogon or tocororo (Priotelus temnurus), Mountain trogon (Trogon mexicanus), Pavonine quetzal (Pharomachrus pavoninus), and Resplendent Quetzal(Pharomachrus mocinno), etc.

image of Apaloderma narina

Narina trogon (Apaloderma narina)

Order 20. Coraciiformes (kingfishers and their allies)

[L. Corax = raven + form]

  1. The order Coraciiformes contains 211 species under ten families, including the birds' group like kingfishers, hornbills, bee-eaters, rollers, hoopoes, todies, motmots, found worldwide.
  2. The body is compact, and the size of the body range from about 10 cm (4 inches) to about 160 cm (about 63 inches) in length.
  3. The neck is short to moderately long with a large head.
  4. The tail is short to very long, which may be forked, square, or graduated.
  5. The outer or central tail feathers are pointed or spatulate at the tip.
  6. The wings and legs are short, and the beak is long.
  7. Some species have anteriorly directed toes, which are fused at the base, but in other species, one of the toes is reversed.
  8. Most of the birds under this order feed on invertebrates such as insects and small vertebrates, but hornbills eat berries and fruit.
  9. They build a nest in the tree holes.

Examples:  Common kingfisher or Halcyon (Alcedo atthis), African pygmy kingfisher (Ispidina picta), Laughing kookaburra (Dacelo novaeguineae),  Amazon kingfisher (Chloroceryle amazona) , Blue-headed bee-eater(Merops muelleri), Lilac-breasted roller (Coracias caudatus) , Eurasian hoopoe (Upupa epops),  Great hornbill (Buceros bicornis),  Oriental pied hornbill (Anthracoceros albirostris), etc.

image of Alcedo atthis

Common kingfisher or Halcyon (Alcedo atthis)

The order Coraciiformes includes the following ten families:

  1. Alcedinidae
  2. Todidae
  3. Momotidae
  4. Meropidae
  5. Coraciidae
  6. Brachypteraciidae
  7. Leptosomatidae
  8. Upupidae
  9. Phoeniculidae
  10. Bucerotidae

Order 21. Piciformes: (woodpeckers and their allies)

[L. Picus = a Woodpecker + form]

  1. Order Piciformes contains about 450 species under 71 living genera, including the birds' group like jacamars, puffbirds, barbets, honeyguides, toucans, found worldwide.
  2. The size of the piciform species varies from about 9 to more than 60 cm (3.5 to 24 inches) in overall length. 
  3. They inhabit the trees of forests, grassland, parks, and orchards because they are physically adapted to, easily live in trees.
  4. Most piciform species are insectivorous and mainly feed on insects but, they also take fruits, nuts, and other items.
  5. Piciformes grab insects from the cavities of trees using the long tongue. Some species use strong/heavy bills to drill holes in trees and capture the insects from the holes by long tongue.
  6. They have special zygodactylous feet. In this case, on each foot two of the toes point forward and the two other toes point backward which makes easy for these birds to climb up and down tree trunks.

Examples: Red-collared Woodpecker (Picus rabieri), Red-naped sapsucker (Sphyrapicus nuchalis),   Toco toucan  or common toucan (Ramphastos toco), Pied Puffbird (Notharcus tectus), Red-crowned Barbet (Megalaima rafflesii), etc.

image of Sphyrapicus nuchalis

Red-naped sapsucker (Sphyrapicus nuchalis)

The Order Piciformes includes the following eight families:

  1. Galbulidae
  2. Bucconidae
  3. Indicatoridae
  4. Picidae
  5. Lybiidae
  6. Megalaimidae
  7. Capitonidae
  8. Ramphastidae

Order-22:Passeriformes(songbirds, or perching birds)

[L. Passer = a spar-J row + form]

  1. Order Passeriformes contains 6,600 known species under more than 140 families.
  2. The order Passeriformes is the largest order of birds containing more than half of all known bird species.
  3. They are commonly known as perching birds or as songbirds.
  4. The foot bears four toes, among them three toes that point forward and one toe that point backward.
  5. They are small to medium-sized birds, and their size ranges from about 3 to 46 inches (7.5 to about 117 cm) in overall length.
  6. Bills are greatly varied in shape and sizes. In some species, it is tiny, needle-like, while in other species, it is huge, vise-like, which is designed to crack the hard shells of seeds.

Examples:  Scissor-tailed flycatcher (Muscivora forficate),    Rifleman (Acanthisitta chloris),  Sharpbill (Oxyruncus cristatus), Superb lyrebird (Menura novaehollandiae), Red-whiskered bulbul (Pycnonotus jocosus),   Loggerhead shrike (Lanius ludovicianus),  Palmchat (Dulus dominicus), House crow (Corvus splendens),  Common starling (Sturnus vulgaris), House sparrow (Passer domesticus), Common chaffinch (Fringilla coelebs),  Fire-tailed sunbird (Aethopyga ignicauda),  etc.

Red-whiskered bulbul (Pycnonotus jocosus)

Concluding Remarks

Birds belong to subphylum Vertebrata under phylum Chordata. There are more than 10,000 living birds species under the class Aves, constituting the importance of members of many ecosystems. They make the integral parts of the food web and food chains. Many birds take their food from plants while others eat insects, earthworms, rodents, and other small vertebrates. Birds also offer food for humans by providing eggs and meat. Many birds play an essential role in cross-pollination and help in plant reproduction. At present, many birds’ species become endangered due to illegal human activities. Therefore, we should take proper conservation measures to protect them from their extinction near the future. 

Wildlife and Its Conservation

Ecological balance is maintained when the environmental factors remain in a state of balance. If one or more of these factors are disturbed to any extent, then they may be recovered soon. But gross natural calamities like flood, earthquake, volcanic eruption, etc. destroy the ecological balance considerably and environmental organisms are liable to destruction. The animals and birds are the ornaments of nature, the beauty of the jungle. With the advancement of civilization, industrialization moves in rapid space. This has resulted in the feeling of the large trees, cleaning the forests.

Wildlife

Wildlife means life in any form (plant or animal) existing in the natural surrounding which provides recreational and economic benefits to man. All undomesticated or untamed animals living in their own natural habitats or in any habitat where they have been adapted are known as wildlife animals.

Conservation

The proper utilization, preservation, and management of the natural resources of the earth are known as conservation. According to Eugene Pleasants Odum (1972), conservation can be defined as a process which is concerned with the use, preservation, and proper management of the natural resources of the earth and their protection from destructive influences, misuse, decay, fire or waste.

Aims of conservation

  • A continuous yield of useful plants, animals, and materials are to be ensured.
  • To preserve the economically important plants, animals, as a source of recreation, creation of aesthetic sense and to meet the various need of life.
  • To maintain the ecosystem balance.

Importance of conservation

  • To maintain the ecological balance
  • To add to the source or recreation of mankind
  • To meet the future demands
  • To create an aesthetic sense
  • To yield beneficial plants and animals
  • To maintain the economic condition of the country
  • To help in the benefit of mankind

Purpose of Wildlife Conservation

Plants and animals offer huge value to human being and it must be saved and protected for future generations to gather experience their presence and value. For the following purposes, we should conserve wild animals.

Medicinal purposes: Wild species (plants and animals) provides useful medications. Today, most of our life-threatening medicines are made from the natural compounds using diverse wild species. These wild species save our lives and contribute to a prospering medicine industry.

Ecological purposes: Foundation of a healthy ecosystem depends on biodiversity. Destruction of wild species makes the ecosystem imbalance. In this case, we should preserve the wildlife to make a balanced ecosystem.

Commercial purposes: Various wild species play a major role and contribute to national and international economics. Today, valuable these wild species are declined due to various human activities such as destruction of habitat, pollution, etc. This degradation of wildlife may impact on the economy; hence, our economy faces a critical problem. So, for the betterment of commercial importance; we should save wild animals and plants.

Aesthetic/recreational purposes: Wildlife species are an invaluable and irreplaceable resource and they provide spiritual, recreational, quality of life values. They also boost up the national economy and enhance the different country`s job-intensive tourism industry. To enhance our quality of life and future generations healthy, measures should be taken for the preservation of plants and animals.

Impact of Wildlife on Nature and Human Civilization

Impact of wildlife may be discussed on the following three headings:

Ecological: Every organism has got its own importance in nature, however harmful it might be. In maintaining the balance in the ecosystem occurs through the extinction of any such component, the balance in the ecosystem is disturbed. This imbalance threatens the life or livelihood of other organisms. Since through the break of food-chain on one level, the other levels grow by leaps and bounds and finally, they will be destined to attack human population directly or indirectly through the damage of his crops and organisms of interest. Through the biological control, the natural balance is maintained by prey and predator chain. Hence, ruthless annihilation of wildlife surely disturbs the balance and invites disaster to human life.

Aesthetics: Human life is full of bustle and hurry, but when we stand and leisurely look to the vast nature, we feel rejuvenated. The beauty and varied richness of the jungle inhabited by colorful and varied types of wild animals gives us pleasure and satisfaction. The multi-colored birds and their songs have always been a source of inspiration to the poets and the common people. The children particularly become joyous with the sight of the large animals (and wild) of the zoo-gardens and elsewhere. The children thus, become interested in and start loving the wild animals.

Economical:  Properly maintained wildlife is a source of the country`s income. We can have economically valued materials like meat, skin, feathers, horn, etc. from wild animals, there is a demand of such materials in foreign countries where we can export these materials and earn foreign exchange. In fact, we have been doing so.

Besides, the resorts of the wildlife, particularly where vanishing and rare animals are kept, are always attractive to both national and international tourists. It is an easy source of earning revenue. 

Causes of Wildlife Extinction

Habitat destruction

Recently, habitat destruction is the major cause of wildlife extinctions. This is done by several factors-

  • Over-exploitation of resources
  • Overgrazing
  • Expanding agriculture
  • Deforestation
  • Drainage
  • Urban and suburban development
  • Dam construction
  • Roads and Highway construction
Illegal trading

Lots of wild animal and plants are harvested from their natural habitat and sold for the purpose of food, pets, and medicine, skin and tourist curios every year.

Hunting

It also causes a reduction of wild animals. Besides, uncontrolled over=exploitation is also responsible for the depletion of varieties of animals.  If you hunt wildlife for the purpose of collecting food to a large extent, it leads to wildlife extinction.  Hunting of animals is done for fun, financial gain, skin, bones, horn, fur, and feathers, etc. Hunting is also done for sports purposes. 

Poaching

It also leads to declining in wildlife extinction on the planet.  It is done for various purposes such as elephants for ivory, rhinos for their horns and tigers for their skins and bones.

Pollution

It is now one of the primary cause of wildlife extinction. Many unnatural chemicals are introduced in the agricultural farm which contaminates air, soil, and seas. The residues interfere with the metabolism of animals and inhibit the growth and disrupt the whole food web and leading to the collapse of the whole of the ecosystem.

Foreign species

Introducing foreign or invasive species in a new place often leads to ecological imbalance.  They also carry pathogens causing diseases of native animals and disrupt food web. They also disrupt the habit and habitat of native species and change the environment of the old species and make adaptation challenge and species-species conflict and they lead to the extinction of native animals.

Climate Change

Climate change is a natural phenomenon which leads to emit greenhouse gas. Due to climate change, there are many species have gone to extinct. Generally, climate change interrupts breeding seasons and migration patterns of many animals leading to extinction.

Human overpopulation

Pressure of over human population causes crowding out of wild species and enhances wildlife extinction. 

Random utilization of natural resources will threaten our future civilization. To maintain the ecological balance we should take care to conserve the natural resources. With the advancement of civilization, more and more resources are being used which also causes depletion of wild fauna such as:

  • A large number of forests is being uprooted for the development of cities.
  • Forest plants are utilized as fuel as well as for making furniture.
  • Water reservoirs are pumped out for agricultural purposes.
  • Damps are being constructed for the generation of hydroelectricity.
  • Poisonous chemicals are used as pesticides; as a result, terrestrial and aquatic organisms are being affected.
  • Man kills the wild animals at random for flesh, skin, etc.
  • The rainfall is affected by the destruction of plants.
  • Soil erosion becomes rapid due to the destruction of coastal forests.
  • Man has created an imbalance in the biotic community

Conservation Measures of Wldlife

As indicated by a present report, about 58% worldwide population have been falling since 1970 and if the pattern proceeds with that decrease could achieve two-third among vertebrate animals by 2020. If not urgent steps are taken, we may lose most of our wildlife.  At present with the help of IUCN, different countries of the world have formulated the following ways and means for wildlife conservation.

  • Botanical garden, gene banks, captive breeding,  zoo, etc. should be created for ex situ conservation.
  • International collaboration among adjacent countries should be made to control illegal trading and poaching.
  • Empowering local communities should be involved to protect natural resources as well as wildlife.
  • Eco fencing and wildlife corridors should be made.
  • Establishment of national parks, wildlife sanctuaries, protected areas, and forests.
  • Enactment of wildlife preservation.
  • To educate the people by rousing their feeling and consciousness for wildlife and to hold public propaganda to this effect.
  • To develop and establish new Zoo-gardens which can educate the commoners and the children while catering pleasure and enjoyment.
  • To develop real forest area through a planned plantation of trees, so that the area may really turn to a natural abode of wild animals.
    Through the exchange of rare and attractive animals with foreign countries or even selling them outright when possible, the government can enrich our zoo-garden in one hand and can earn foreign exchanges on the other.
  • Restriction of killing wild animals, keeping the habitat intact, renovation of destructed habitats, etc.
  • For the preservation of wildlife, several forests have been declared as reserve forests, sanctuaries, protected areas, and national parks.
  • Entrance to the reserve forests is prohibited without permission. A forest may be announced as reserve forest for a particular period.
  • Fishing, Killing of animals and cutting of trees are totally prohibited in the sanctuaries.

Final Words

Conservation of nature is the prime necessity for maintaining the ecological balance of the organic components. Hence, conservation of wildlife forms is a part of it. Protection, careful exploitation and management of wildlife will save these natural resources from misuse, decay, and destructive influences.

You may also read: Fish and Its Body Parts