Question

what is Porifera? explain briefly
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Answer 1

Answer:

The approximately 5,000 living sponge species are classified in the phylum Porifera, which is composed of three distinct groups, the Hexactinellida (glass sponges), the Demospongia, and the Calcarea (calcareous sponges).

the features of phylum porifera are

• sessile(stalk less), sedentary(attached to the substratum), and marine except one group that lives in fresh water. commonly called sponges.
• simplest multicellular, diploblstic animals.
• the body design involves minimal differentiation and division into tissues. the cells are loosely held together in  gelatinous matrix, mesogle or mesohyl.
• radially symmetrical. sponges may be vase-like, rounded or branched.
• body is perforated with numerous pores.the ostia, that open into a canal system having canals and chambers lined with collared flagellated cells or choanocytes.
• mouth , digestive cavity, and anus absent.
• reproduction is both asexual and sexual through fertilization. possesses great power of regeneration.
• skeleton is made up of minute calcareous or silicious spicules ar spongin fibre (collagen) or both.

hope it helps,...............................