This phylum contains the animals referred to as sponges. The sponges are unique among animals. They are more like individual cells living in a colony, and less like a typical multicellular organism.

 

Sponges are anchored in one place and do not move from place to place. They do not have a stomach. Food is digested in cells that line the inside cavity; these cells are called collar cells. Pore cells pump water over the collar cells to keep the sponge fed.

 

Most sponges have skeletons called spicules. Most spicules are made of silica and are similar to glass. Other Sponges have spicules made of calcium carbonate or spongin. If a sponge is shredded the cells will reform in to the same sponge. Pieces that are broken off can form new sponges. Sponges are unique among animals.