1 minute read

Peanut Worms: Sipuncula

No Common Name (sipunculus Nudus): Species Account

Physical characteristics: Sipunculus nudus measures 6 to 10 inches (150 to 250 millimeters) long. The introvert is short, only one-third the length of the trunk, and lacks hooks. There are 24 to 34 bands of long muscles visible through the skin.

Geographic range: Sipunculus nudus (abbreviated as S. nudus) are found throughout the world in temperate, subtropical, and tropical waters. (Specific distribution map not available.)

Habitat: S. nudus live in burrows in the sand and are found from just below the tidal zone down to 2,953 feet (900 meters) deep.

Diet: S. nudus swallow the surrounding sand to digest bits of plant and animal tissues.

Behavior and reproduction: This species spends its days hidden in its burrow, extending its tentacles to feed at night.

Males and females release sperm and eggs into the water. They pass through two larval stages before becoming young worms.

Sipunculus nudus and people: S. nudus is the best-known species of peanut worm and is often used as a research animal. They are sold as fish bait in some parts of the world.

Conservation status: S. nudus is not considered endangered or threatened. ∎



Cutler, Edward B. The Sipuncula. Their Systematics, Biology, and Evolution. Ithaca, NY: Cornell University Press, 1994.

Kozloff, E. N. Marine Invertebrates of the Pacific Northwest. Seattle, WA: University of Washington Press, 1996.

Ruppert, E. E., and R. S. Fox. Seashore Animals of the Southeast. Columbia, SC: University of South Carolina, 1988.

Web sites:

Introduction to Sipuncula. The Peanut Worms. http://www.ucmp.berkeley.edu/sipuncula/sipuncula.html (accessed on January 5, 2005).

Additional topics

Animal Life ResourceMollusks, Crustaceans, and Related SpeciesPeanut Worms: Sipuncula - Physical Characteristics, Behavior And Reproduction, No Common Name (sipunculus Nudus): Species Account - GEOGRAPHIC RANGE, HABITAT, DIET, PEANUT WORMS AND PEOPLE, CONSERVATION STATUS