Porifera : Characteristics and Classification
Scottish Anatomist and Zoologist Robert Edmond Grant proposed the name Porifera (L. Porus, pore and ferre, to bear). The representatives of Phylum Porifera are also known as Sponges. They are simple types of aquatic invertebrates. This phylum contains about 10000 species; among them, most of the species are Marine and some are freshwater (about 100 species). Their body is asymmetrical or radially symmetrical with a variety of sizes and colors. They can prefer to live in tidal zones to almost 9,000-meter depth ranges. Most of the sponges are attached to submerged hard rocks.
General characteristics of Porifera
Classification of Phylum Porifera
Phylum Porifera is divided into the following four classes on the basis of the skeleton system.
Class 1: Calcarea
The class Calcarea is divided into the following two orders:
Examples: Clathrina clathrus, Ascute asconoides, Leucosolenia cervicornis, Dendya clathrata.
Examples: Scypha gelatinosum, Leucosolenia cervicornis
Class 2: Hexactinellida
Examples: Hyalonemma, Pheronema, Euplectella,
The class Hexactinellida includes the two orders:
Examples: Euplectella aspergillum (Venus’s flower basket)
Examples: Hyalonema aculeatum (Glass rope sponge), Pheronema annae (Bowl sponge).
Class 3: Demospongiae
Examples: Spongilla, Euspongia
The class Demospongiae is divided into the following three subclasses:
Subclass Tetractinellida is divided into the following three orders:
Examples: Oscarella carmela, Halisarca australiensis.
Examples: Plakina monolopha, Plakortis dariae.
Examples: Geodia barretti, Craniella elegans
The subclass Monaxonida includes the following four orders:
Examples: Tethya aurantium (the golf ball sponge or orange puffball sponge) , Cliona patera (Neptune's cup sponge), Cliona celata (Boring sponge).
Order 2. Halichondrida
Example: Halichondria panicea (breadcrumb sponge)
Order 3. Poecilosclerida
Examples: Myxilla incrustans, Cladorhiza tenuisigma, Clathria atrasanguinea
Order 4. Haplosclerida
Examples: Haliclona oculata (eyed finger sponge), Spongilla lacustris (freshwater sponge) , Ephydatia fluviatilis (Freshwater sponge).
Examples: Spongia catarinensis, Spongia officinalis (Bath sponge),
Hippospongia communis (horse sponge), Phyllospongia papyracea.
Hartman and Goreau (1970) proposed another class Sclerospongiae under the Phylum Porifera but the recent studies suggest that the class ‘Sclerospongiae’ should be placed under the class ‘Demospongiae.
Examples: Astrosclera willeyana, Stromcitospongia, Hispidopetra miniana.
The term ‘Porifera’ is derived from two Latin words ‘Porus’ meaning pores and ‘Ferre’ meaning bear. They are predominantly marine organisms which inhabit in the intertidal to the deepest ocean zone. There are about 8500 described living species under the phylum Porifera worldwide. Among them, over 98 % live in the ocean, and the rest inhabit in freshwater lakes, ponds, streams, etc. They perform an important role in filtering microorganisms and other contaminants from water. They form a significant portion of many reef coral communities and provide brightly colored and come in a diverse array of shapes.
You may also read: Ecology and Ecosystem