Nervous and Digestive/Feeding System

Sponges have no nervous system and no brain.

The skin of a sponge has lots of small pores and large openings. The small openings are the entrances to a system of channels. Those channels lead to other chambers which are lined with feeding cells called choanocytes. On each of those cells, a flagellum is surrounded by a collar, and when the beating of the flegallem draws water though the collar, tiny particles are carried down the body to be digested. These collar cells pump water through the sponge and filter out food.