Sea Cucumbers
Most sea cucumbers reproduce by releasing sperm and ova into the ocean water. Depending on the conditions, thousands of gametes can be produced by this process. The reproductive system of these cucumbers consist of a single gonad. The gonad contains a cluster of tubules emptying into a single duct that opens on the surface of the cucumber. Other species of cucumbers fertilize their eggs internally, then pick up the zygote with one of their feeding tentacles. The egg is then inserted into a pouch on the cucumber's body, where it will develop. Some species brood their young inside the body cavity and give birth through a small rupture near the anus. In other species, the egg develops into a free-swimming larvae after about three days of development.
Sea Cucumber Larvae