Question

why are sponges called porifera

Answer 1

Organisms belonging to phylum Porifera are the organisms with a low degree of individuality and cellular organisation. They appear plant like and their body bears several pores hences they are called Porifera or Sponges. These pores form a part of canal system through which water enters the body and several processes like nutrition, respiration, circulation and excretion is done at its simplest level through this system.

Answer 2

Sponges are called porifera because I think that sponges are similar to the other animal in that they are multicellular etc and produce sperm cell. Unlike other animal, lack true tissues.
All the sponges are sessile aquatic animal