Phylum - Porifera

➡Introduction
(L., porus=pore, ferre=to bear) 
The name Porifera to this phylum was given by Robert E Grant (1936).Porifera means pore bearers.This is phylum includes a group of animals which bears numerous minute pore throughout the surface of the body and are usually called sponges. 


⁍ General characters
1. All sponges are aquatic,mostly marine but a few are freshwater. 
2.They are multicellular organism with cellular level of body organisation without forming tissue or organs. 
3. They are sessile, solitary or colonial. 
4. They are asymmetrical or radially symmetrical bodies. 
5. They body is cylindrical, tubular or vase-like. 
6. The body wall is diploblastic with outer dermal epithelium and inner gastric epithelium with a gelatinous non-cellular mesenchyme in between. 
7. The body surface bears numerous minute pores that is Ostia for the ingress of water. 
8. They possess peculiar canal system through which water current flows drawing food and oxygen inside the body and carrying away excretory and reproductive products. 
9. Internal skeleton is present in the mesenchyme in the form of calcareous or siliceous spicules or of proteinous spongin fibres. 
10. There are not definite organ system in the body digestion is entirely intracellular. 
11. Nervous and sensory cells are lacking. 
12. Reproduction takes place both by asexual and sexual method. Asexual by budding,fission or gemmules formation. Sexual reproduction by over and sperm.Fertilization is internal. 
13. Cleavage is holoblastic and development is indirect followed by a free swimming ciliated larva, the amphiblastula or parenchymula. 

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