Feeding & Respiration

Sponges are filter feeders. This means that water flows through the porous body of sponge, and any food/nutrient will get filtered out from the water. The food particles, such as tiny plants or animals will be absorbed into the central cavity. As the water moves through the sponge, food particles stick to the collar cells. The trapped particles are then engulfed by the collar cells or they are passed on to the amebocytes.

Sponges have no respiratory or excretory glands/organs. All of these processes occur through diffusion within individual cells. The water also serves as sponges' respiratory system. As water passes through the body cell, sponge cells remove oxygen and give off carbon dioxide into the water. The wastes that are produced by cellular respiration are also released into the water. The water then carries the wastes away.

Sponges have flagellated cells called choanocytes which line the interior. The flagellum are surrounded by microvilli, and the movement of the flagella (of the Collar Cells) pump water through the body of the sponge. The collar of the choanocyte is also where most of the diffusion of nutrients into the sponge takes place.