Rattailed sea cucumber

Molpadia oolitica

ORDER Molpadiida

FAMILY

Molpadiidae

TAXONOMY

Chiridota oolitica (Pourtales, 1851), Florida, United States.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

A brownish gray to reddish black, sausage-shaped sea cucumber to 6 in (15 cm) long with 15 digitate tentacles and a small, sometimes indistinct "tail." The body surface is smooth. The tail and oral region usually are somewhat lighter in color than the rest of the body. Body color is age related; older individuals often are darker as a result of the presence in the body wall of microscopic phosphatic bodies that replace the calcareous ossicles as the animal ages. Ossicles in the body wall are few or absent in larger animals. When present, ossicles are more common in the tail in the form of three-spired towers with a tripartite to elongate base.

DISTRIBUTION

Eastern Gulf of Mexico and western Atlantic coast from Florida to Labrador, west to the North Sea and the Arctic Ocean.

HABITAT

Soft sand, mud or silt in subtidal areas to beyond the continental slope to at least 1,500 ft (457 m) in depth.

BEHAVIOR

A burrowing sea cucumber that can occur at densities of several animals per square foot (0.1 m2) in some areas. These populations considerably modify bottom topography and the vertical grain-size distribution of sediment. The relatively stable fecal mounds become home to clams, amphipod crustaceans, and tube-dwelling worms.

FEEDING ECOLOGY AND DIET

Ingests and processes large amounts of fine sediment in a conveyor-belt manner while positioned vertically, oral end down, in the substrate. Feeding is apparently selective for the finer fraction of sediment, which passes through the gut without being pelletized. The anus lies at the surface, where evacuated material forms a large, wide mound.

REPRODUCTIVE BIOLOGY

Nothing is known. Other species of Molpadia, such as M. intermedia and M. blakei, have large, yolky ova and a nonfeeding, planktonic vitellaria larva.

CONSERVATION STATUS

Not listed by the IUCN or under the CITES convention.

SIGNIFICANCE TO HUMANS None known. ♦

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