Question

What physical feature pertaining to the organism and its medium do you notice in a sponge body from which sponges can be/were identified as animals and not plants? What do you call the region in the sponge body in which you noticed that feature?

Answer 1

There are many distinguishing features in sponges which separate them from plants as they are heterotrophs, have no tissues or organs, radial symmetry and the most prominent have choanocytic cells. Choanocytes or collar cells makes the lining of the inner chamber. These are the flagellated cells that have a collar like ring of microvilli surrounding a Flagellum. The Flagellum creates water currents through the sponges, collar filters filters microscopic food particles from water.