Sperm are released into excurrent flow of the spongocoel and are then drawn in with incurrent flow of another sponge. Sperm penetrate into mesohyl and fertilize the eggs. The zygote develops into a flagellated larva which is released into the spongocoel and escapes with the excurrent water through the osculum. Surviving larvae settle on the substratum and develop. In most cases the larva turns inside-out during metamorphosis, moving the flagellated cells to the inside.
Sponges possess extensive regeneration abilities for repair and asexual reproduction.
There are more than 10,000 species in the phylum Cnidaria, most of which are marine. The phylum contains hydras, jellyfish, sea anemones and coral animals. Simple, sac-like body. Cylindrical form which adheres to the substratum by the aboral end of the body stalk and extends tentacles around the oral end to contact prey. Moves freely in water by passive drifting and weak bell contractions.