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Turbellarians: Turbellaria

Oyster Leech (stylochus Inimicus): Species Accounts

Physical characteristics: The body of an oyster leech is oval or disk shaped with retractable tentacles. There are three types of eyes. The throat is long and in the middle of the body. Each oyster leech has both male and female reproductive organs close to each other in the rear of the body. Although they are called leeches, oyster leeches are not in the same group as the more familiar blood-sucking leeches, which are segmented worms, the same group that contains earthworms.

Geographic range: Oyster leeches live off both coasts of Florida, United States.

Habitat: Oyster leeches live under rocks and algae, in oyster shells, and in other invertebrates.

Oyster leeches enter, devour, and kill oysters, harming the livelihood of people who harvest and sell oysters. (Illustration by Marguette Dongvillo. Reproduced by permission.)

Diet: Oyster leeches feed on animal matter, including oyster tissue.

Behavior and reproduction: Oyster leeches tend to hide under debris or in shells of oysters and barnacles. After mating, which can last nine hours and involve more than four partners, an individual oyster leech can deposit seven thousand to twenty-one thousand eggs. Egg masses usually are attached to clean oyster shells. The worms cover their eggs to protect them. Larvae with six eyes hatch from the eggs. The larvae swim up and away from the bottom.

Oyster leeches and people: Oyster leeches enter, devour, and kill oysters, harming the livelihood of people who harvest and sell oysters.

Conservation status: Oyster leeches are not threatened or endangered. ∎



Aaseng, Nathan. Invertebrates. New York: Venture, 1993.

Niesen, Thomas M. The Marine Biology Coloring Book. 2nd ed. New York: HarperResource, 2000.

Silverstein, Alvin, Virginia Silverstein, and Robert Silverstein. Invertebrates. New York: Twenty-First Century, 1996.

Web sites:

"Oyster Leech." Smithsonian Marine Station at Fort Pierce. http://www.sms.si.edu/IRLFieldGuide/Stylochus_sp.htm (accessed on December 20, 2004).

Seifarth, Wolfgang. "Regeneration." Marine Flatworms of the World. http://www.rzuser.uni-heidelberg.de/bu6/Introduction03.html (accessed on December 20, 2004).

Additional topics

Animal Life ResourceJellyfish, Sponges, and Other Simple AnimalsTurbellarians: Turbellaria - Physical Characteristics, Habitat, Diet, Behavior And Reproduction, Freshwater Planarian (dugesia Tigrina): Species Accounts - GEOGRAPHIC RANGE, TURBELLARIANS AND PEOPLE, CONSERVATION STATUS