ENTOPROCTS: Entoprocta

PHYSICAL CHARACTERISTICS

Entoprocts are tiny bottom-dwelling animals that have a crown of tentacles and a thin stalk. Both the mouth and anus (AY-nuhs) open inside the crown. Some entoprocts live in colonies and are attached to one another by a branch at the base of their stalks.

GEOGRAPHIC RANGE

Entoprocts live all over the world.

HABITAT

Most entoprocts live at the bottom of warm, moderate, and cold seas from the shore to deep water. One species lives in freshwater. Colonies live on rocks, shell remains, human-made objects such as dock pilings, and sometimes on other animals. Most species not in colonies live on the bodies of animals such as sponges.

DIET

Entoprocts eat drifting microscopic plant particles.

BEHAVIOR AND REPRODUCTION

When they are touched, entoprocts contract their tentacles and bend at the stalk. Some species that live alone rather than in colonies can glide over the bottom. Others somersault across the bottom, and one can walk using a foot with two leglike extensions.

Entoprocts that live in colonies are either male or female, but both sexes are present in a single colony. Entoprocts that do not live in colonies make both eggs and sperm. They are males first and then turn into females. Male entoprocts release sperm into the water. The sperm is taken up by females and joins with eggs inside them. Larvae develop inside the females. Larvae (LAR-vee) are animals in an early stage that change form before becoming adults.

All entoprocts can reproduce by budding. Buds develop at the base of entoprocts that live in colonies or at the base or crown of entoprocts that live alone. The buds grows to full size and then break off to live as new individuals.

ENTOPROCTS AND PEOPLE

Entoprocts have no known importance to humans.

CONSERVATION STATUS

Entoprocts are not considered threatened or endangered.

MARINE COLONIAL ENTOPROCT (Barentsia discreta): SPECIES ACCOUNT

Physical characteristics: Marine colonial entoprocts are 0.1 to 0.2 inch (3 to 6 millimeters) long and have about 20 tentacles. The stalks are three to eight times longer than the crown and have a muscular swelling at the base. The bases are attached to a branch that connects the colony members.

Geographic range: Marine colonial entoprocts live all over the world except northern Europe.

Habitat: Marine colonial entoprocts live on rocks, stones, dock pilings, and worm tubes in shallow or deep sea water.

Diet: Marine colonial entoprocts eat drifting microscopic plant particles.

Behavior and reproduction: When disturbed, marine colonial entoprocts bend from the base, but the stalk itself does not curve. When one member of the colony bends, those around it also bend. Marine colonial entoprocts bud from the branch that connects the colony members. A single colony has both male and female members. Embryos develop into larvae inside the females.

Marine colonial entoprocts and people: Marine colonial entoprocts have no known importance to people.

Conservation status: Marine colonial entoprocts are not considered threatened or endangered. ∎

FOR MORE INFORMATION

Books:

Valentine, James W. On the Origin of Phyla. Chicago: University of Chicago Press, 2004.

Web sites:

Badorf, Michelle, Courtney Lewis, Bridget O'Malley, Kimberly Owen, and Shelly Zimmerman. "Reclassification of Entoprocta into the Subkingdom Proterostomata." Journal of Systematic Biology.http://comenius.susqu.edu/bi/202/Journal/Vol8/number1/1zoobls.html (accessed on February 3, 2005).