Category Archives for "Ecology"

Ecological Pyramid

G. Evylen Hutchinson and Raymond Lindeman first discovered the ecological pyramid. They graphically presented the definite relationship between the various forms of organisms such as producers and consumers at different trophic levels and made the graphical presentation which looks like a pyramid. In this case, the producers make up the base and the successive level of consumers constitute the upper layers.

Ecological pyramids are of the following three types:

  • Pyramid of number: In this case, the number of individual organisms is taken into account;
  • Pyramid of biomass: In the case, total dry weight of living materials are considered;
  • Pyramid of energy: In this case, the rate of flow of energy at successive trophic level is taken into consideration;

Pyramid of Number

The pyramid of number is upright when the producer organisms remain in abundance near the base of food chain and the consumers gradually decrease in numbers towards the apex. Hence, in such situations the number of producer organisms is always more than that of the primary consumers indicating the relationship in numbers between the different trophic levels.

The number of consumers decreases in the successive levels of pyramids from below upwards. The pyramid of number may be inverted if the producer organisms are larger than the consumers in size as in forests.

image of Pyramid of Number

Pyramids of Biomass

Pyramids of biomass may be either upright or inverted. This pyramid indicates the total living weight of each trophic level belonging to a particular food chain of any ecosystem.

The main feature of the pyramid of biomass is the indication of the gradual decrease in biomass in the trophic level from base towards the apex. In the forest ecosystem, the pyramid of biomass is upright and inverted in case of parasites.

image of Biomass pyramid

Pyramid of Energy

The representation of energy flow in an ecosystem with the help of pyramid is called as the pyramid of energy. Energy pyramid is sometimes known as ecological or trophic pyramid. The trophic level at the base denotes the position of the highest amount of energy whereas the amount of energy at the trophic level situated at the apex is the lowest.

Pyramid of energy always remain upright as a gradual decline of energy takes place from the initiation to the termination of a food chain. Actually, it helps to transfer energy from one to another organism along the food chain. In this case, rate of energy level reduces from the bottom to the top of the pyramid through the trophic level.

image of Energy Pyramid

For example, of about 20% of the total solar energy is used up by the green plants in the photosynthesis mechanism which they perform. It decreases in energy from lower to higher trophic levels during respiration.

Again energy is transmitted from one trophic level to the other 80% -90% of the potential energy is lost in the form of heat energy. Hence, pyramid of energy always remains upright while a gradual decline of energy takes place from the starting point to the termination of food chain.

Advantages of the Pyramid of Energy

  • It assesses the pace of production over some period of time.
  • Two types of alike biomass may have very diverse life spans. Thus, a direct relationship of their total biomasses is confusing, but their productivity is exactly comparable.
  • The comparative energy chain inside a biological system can be looked at utilizing pyramids of energy; additionally various ecosystems can be compared.
  • There are no reversed pyramids.
  • The contribution of sun based energy or solar power can be included.

Disadvantages of Ecological Pyramid

  • The pace of biomass production of the creature is required, which includes estimating growth and propagation through time.
  • There is still the trouble of allocating the creatures to a particular trophic level. Just as the living things in the food chains there is the issue of allocating the decomposers and detritivores to a specific trophic level.

Significance of Ecological Pyramid 

The significance of ecological pyramid can be clarified in the following focuses:

  • They show the taking care of various living beings in various environments.
  • It shows the proficiency of transfer of energy.
  • The state of the ecosystem can be observed, and any further harmful activities can be prohibited.
  • More than one organism may involve in various trophic levels as if there should be an occurrence of the food web. Along these lines, this system doesn't consider food webs.
  • The saprophytes are not measured in any of the pyramids despite the fact that they make a significant piece of the different ecosystem.
  • These pyramids are relevant just to basic food chains, which for the most part don't happen naturally.
  • These pyramids don't convey any idea according to varieties in season and atmosphere.
  • They don't think about the possibility of similar species at various levels.
  • Trophic level denotes a functional level.
  • A given species may involve more than one trophic level in a similar ecological system simultaneously.
  • In most ecological systems, all the pyramids of biomass, number, and energy are upstanding. In this case, producers are more in biomass and number than the herbivores while herbivores are more in biomass and number than carnivores.
  • Also energy at lower trophic level is in every case more at higher trophic level.

Aquatic Ecosystem : Types and Components

Ecosystems are of two main types such as terrestrial ecosystems and aquatic ecosystems. In this case, terrestrial ecosystems constitute the land masses which cover about 28% of the surface of the Earth. Some notable examples of terrestrial ecosystems are tundra, desert, alpine regions, rainforest etc., while the aquatic ecosystems are found in water environment that covers more than 70% of Earth’s surface.

The notable aquatic ecosystems are ponds, lakes, rivers, bogs, canals, streams, wetlands, swamp, estuaries, and ocean, etc. The aquatic ecosystem provides the habitat for various animals, plants, and microbes that are water dependents.

Types of Aquatic Ecosystem

There are different types of aquatic ecosystems:

Freshwater Ecosystem

Freshwater ecosystems include lakes, ponds, wetlands, streams, swamp, rivers, bog, and temporary pools. These cover about 0.8% of the earth surface.  These ecosystem provide habitat for 41% of the world`s fish species.

The freshwater ecosystems are of the following three basic types:

  1. Lantic
  2. Lotic and
  3. Wetlands

Lentic Ecosystems

Lentic ecosystem includes standing water bodies. The examples of lentic ecosystems are ponds, lakes, ditches, seasonal pools, basin marshes etc. Among them, lakes have deep waters which influence by light while ponds support a wide range of water plants due to their more light penetration. Besides, algae, shrimps, crabs, frogs and salamanders are the important biotic factors of lentic ecosystem.

Lotic Ecosystems

These are rapidly flowing water bodies where unidirectional water movements are available.  They have faster moving turbulent waters which contain high concentrations of DO (dissolved oxygen). These water bodies support wide range of biodiversity.   These ecosystems include creek, rivers, brook, streams, spring, etc.

They provide suitable habitats for numerous species including mayflies, beetles, stoneflies and different species of fishes such as eel, trout, minnow, and different anadromous fish, etc. At present, these ecosystems are degraded through various environmental threats such as over extraction of water, dams, pollution and various introduced species.

There are two main zones of lotic ecosystems such as rapids and pools. The rapid zones have fast water flow with clear bottom while the pools are deeper areas which contain slower currents with silt builds up.


Wetlands are the water bodies which contains large varieties of animals and plants.  It is the most well productive natural water bodies that provide habitats for large numbers of animal and plant species.  It is dominated by vascular plant species due to its high productivity.  In this ecosystem, animal lives include invertebrates such as damselflies, dragonflies, various birds’ species and lots of fishes, mammals, etc. 

Wetlands are of main four types which include: marsh, swamps, bog and fen.  In many cases, wetlands are converted into dry land that has dykes and drains. It is also used for the purpose of agriculture which provide the cultivation of rice and meet the diet of half the world`s population.   It gives the benefit to humanity by filtering water, and also helps in storm protection and flood control. 

Marine Aquatic Ecosystem

Marine ecosystem is the largest aquatic ecosystem which covers about 71% of the Earth`s surface. It contains about 97% water of the planet. This ecosystem contains about 85% of the dissolved materials such as sodium and chlorine.

This ecosystem has many zones, among them oceanic zone is the largest open zone which provides habitats for many aquatic animals such as sharks, whales, and various fish species. The benthic zone contains many invertebrates while the intertidal zone contains high and low tides.

Various dinoflagellates, brown algae, cephalopods, corals, echinoderms, shellfish such as crabs,, shrimps, lobsters, snails are also found in marine ecosystem.

Components of Aquatic Ecossytem

A pond is the typical aquatic ecosystem which comprises of four components. These include:

  1. Abiotic substances
  2. Producers
  3. Consumers and
  4. Decomposers.

Abiotic Substances

The abiotic substances are both inorganic and organic. The chief inorganic substances are H2O, CO2, O2, N2, Ca, P, etc. These substances in a state of solution or solubility are available for the nutrition of organisms from the environment.


The producers in a pond are mainly of two types such as (a) relatively larger plants that grow in shallow water; such plants may be rooted (Vallisneria. Hydrilla, etc) or free floating plants, such as pistia, water hyacinth, etc. (b) Minute floating plants, mainly algae constituting the so called phytoplankton. These are distributed throughout the pond as deep as light penetrates. The phytoplankton is much more important than the rooted plants in the production of basic food for the ecosystem.

image of Aquatic ecosystem


The consumers are primary, secondary and tertiary. The primary consumers feed on plants which act as producers. These are of two types: (a) Zooplankton (b) benthos. Amoeba, Daphnia, Cyclops, Diaptomus, Bismina etc constitute the zooplankton while snails, small fishes, chironomus larvae, constitute the benthos. The secondary consumers are carnivorous which feed on the plant eaters such as prawn, some fishes. The tertiary consumers eat primary consumers such as Walloga attu, Channa spp, snakes, etc.


Different types of aquatic bacteria and fungi act as decomposers. They are more abundant in the bottom mud rich in dead decayed plant and animal accumulation. By the action of aquatic microorganism, the dead bodies are rapidly decomposed and much simpler substances released for future use of the autophytic plants.

Plankton and Benthos

These are two major life forms in water. The organisms which are more or less dependent on water currents or wind action for their movements are called plankton. Phytoplankton are free floating plant organisms. Organisms attached with or resting on the bottom    or living in the bottom sediments are called benthos or bottom forms.

Functions of Aquatic Ecosystems

Aquatic ecosystems show many beneficial environmental jobs. They make water purification, recycle nutrients, recharge ground water, prevent floods and also offer habitats for aquatic wildlife. It also provides human recreation and use as the tourism industry in coastal regions.

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