Larvaceans: Appendicularia

Larvaceans move their tail inside their house to make a current that filters food particles and moves the house through the water. If the filters become clogged or something bumps the house, the larvacean leaves the house through a trap door. The beginnings of a new house lie on the trunk of the animal's body, and the larvacean inflates the new house and flips inside.

Some larvaceans have glowing grains in their house wall. Some scientists believe that predators eat an empty house that is flashing light while the larvacean swims away to make another house. Surface waters of some bays and harbors sometimes glow brilliantly because of the presence of large groups of larvaceans.

Larvaceans make both eggs and sperm, which are released directly into the water. The sperm are released first, and then the eggs burst out of the body wall, a process that results in the death of the animal. Fertilization (FUR-teh-lih-ZAY-shun), or the joining of egg and sperm to start development, and development take place in the open water. These animals reproduce rapidly. If there is a great deal of plant plankton in an area, huge swarms of larvaceans can form, sometimes in a matter of a few days.