. Non Chordates (Invertebrata) . . Phylum: Porifera (L.
poros -pore; ferre -to bear) These pore bearing animals are commonly called sponges. They are aquatic, mostly marine, asymmetrical and a few species live in freshwaters. They are primitive, multicellular, sessile animals with cellular level of organisation in which the cells are loosely arranged. They are either radially symmetrical or asymmetrical animals.
They possess a water transport system or canal system where water enters through minute pores called ostia lining the body wall through which the water enters into a Grade : Radiata Among the eumetazoa, a few animals have an organisation of two layers of cells, the outer ectoderm and inner endoderm, separated by a jelly like mesoglea. They are radially symmetrical and are diploblastic. Examples: Cnidarians (sea anemone, jelly fish) and Ctenophores (comb jellies). Grade : Bilateria The eumetazoans other than Radiata, show organ level of organisation and are bilaterally symmetrical and triploblastic.
The grade Bilateria includes two taxonomic levels called Division. Division : Protostomia ( Proto : first; stomium : mouth) Protostomia includes the eumetazoans in which the embryonic blastopore develops into mouth. This division includes three subdivisions namely acoelomata, pseudocoelomata and schizocoelomata. Figure .
Classification of Kingdom Animalia based on common fundamental features XI Std Biology-Zoology Chapter- central cavity ( spongocoel) and goes out through the osculum. This water transport system is helpful in food gathering, circulation, respiration and removal of waste. Choanocytes or collar cells are special flagellated cells lining the spongocoel and the canals. The body is supported by a skeleton made up of calcareous and siliceous spicules or spongin or both.
Nutrition is holozoic and intracellular. All sponges are hermaphrodites (i.e.) the ova and sperms are produced by the same individual. They also reproduce asexually by fragmentation or gemmule formation and sexually by the formation of gametes. Development is indirect with different types of larval stages such as parenchymula and amphiblastula .
Examples: Sycon (Scypha), Spongilla (fresh water sponge), Euspongia (bath sponge) Euplectella (Venus flower basket) (Figure . ). Figure . Examples of Porifera Sycon Hyalonema Chalina Euplectella .