|Many sea animals look like plants. Sponges are animals. Sponges clean the water. Tiny holes called ostia allow water into the sponge. The water exits through the osculum once it is filtered.|
The anatomy of the sponge is very interesting. They have two layers of cells (epidermis) separated by a thin, jelly-like substance called Mesenchyme. In the Mescenchyme is a network of spicules, made of calcium carbonate or silica, (depending on the species) that provide a framework to support the sponge.
The various canals and cavities in the body of the sponge have flagella that beat constantly, pulling the water into the sponge from which the sponge extracts organic debris. Since the sponge has no organs, the amebocytes, or cells within the sponge, that performs digestion, travel freely in the mesenchyme, transporting the food it uses through out the parts of the sponge. The amebocytes also bring the waste products to the epidermis where they are released. The amebocytes also exchange gases, as a type of respiration.
- Exploring Creation with Zoology: Swimming Creatures, Jeannie Fulbright
- Exploring Creation with Biology, Jay Wile and Marilyn Durnell