GENERAL HISTOLOGY

Detailed explanation-1: -Although other animals at the reef are said to filter-feed, the method used by sponges is unique to this simple group of animals. In fact, sponges are named because of the many pores covering their bodies. They belong to the Phylum Porifera and may be called poriferans.

Detailed explanation-2: -Instead of a mouths they have tiny pores (ostia) in their outer walls through which water is drawn. Cells in the sponge walls filter food from the water as the water is pumped through the body and the osculum ("little mouth").

Detailed explanation-3: -The Porifera are primarily filter feeders, utilizing food particles suspended in the water and captured by the choanocytes. Food particles consist essentially of bacteria, other microorganisms, and particles of organic debris; sponges also probably absorb dissolved organic substances.

Detailed explanation-4: -Sponges (Poriferans) receive (incoming) food particles with the help of collar cells (choanocytes). These collar cells or choanocytes are surrounded by microvilli which filter the incoming food particles. Therefore, sponges/Poriferans are called filter feeders.

Detailed explanation-5: -Sponges must pump water through their bodies in order to eat. Because sponges are sessile, meaning they cannot move, they filter water to obtain their food. They are, therefore, known as filter feeders.