ORDER
Sipunculiformes
FAMILY
Sipunculidae
TAXONOMY
Sipunculus nudus Linnaeus, 1766, type locality unknown, but perhaps Mediterranean Sea.
OTHER COMMON NAMES
None known.
PHYSICAL CHARACTERISTICS
Commonly up to 6 in (15 cm) long, sometimes reaching 10 in (25 cm); introvert up to one-third of trunk length. Longitudinal and circular body wall musculature in bands. Distinguished by number of longitudinal muscle bands: 24–34. Introvert hooks absent.
DISTRIBUTION
Cosmopolitan in temperate, subtropical, and tropical waters in subtidal zone to 2,953 ft (900 m) depth. (Specific distribution map not available.)
HABITAT
Semi-permanent sand borrows.
BEHAVIOR
During daytime, usually hides in burrow but might extend tentacles at night.
FEEDING ECOLOGY AND DIET
Ingests sediment and utilizes associated organic material.
REPRODUCTIVE BIOLOGY
Dioecious; indirect developer with lecithotrophic trochophore and long-lived planktotrophic pelagosphera.
CONSERVATION STATUS
Not listed by the IUCN.
SIGNIFICANCE TO HUMANS
Best examined sipunculan species; model organism for anatomy, physiology, biochemistry, and ecology. Used as bait in some parts of the world.
