Why are all sponges regardless of size, limited to feeding on microscopic food particles?
Sponges, regardless of size limited to feed on microscopic food particles because of their cellular level of organization. Sponges are marine,asymmetric animals having water transport or canal system . They are found attached with the rocks at the bottom of the water body. When water enter their body through minute pores(ostia), it carries small microscopic organisms along with it. Sponges extract their food from this water, digest it intracellularly & rest of the water leaves the body through pore known as Osculum.