Pelagic sea cucumber

Pelagothuria natatrix

ORDER Elasipodida

FAMILY Pelagothuriidae

TAXONOMY

Pelagothuria natatrix Ludwig, 1894, Gulf of Panama, Eastern Pacific Ocean below 2,000 ft (610 m) depth.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

A bizarre, transparent sea cucumber 2-3 in (5-8 cm) long with 12-16 webbed papillae exceeding the body's length and forming a veil around the mouth. This sea cucumber is slender and pale pinkish purple. The tentacles are two-pronged and number approximately 15. Ossicles and a calcareous ring are absent.

DISTRIBUTION

Western Indian Ocean to eastern Pacific Ocean and Atlantic Ocean at subtropical to tropical latitudes.

HABITAT

Open ocean from near surface waters to at least 10,000 ft (3,050 m) depth.

BEHAVIOR

The pelagic sea cucumber often is encountered hanging motionless and drifting. It swims by flapping its veil posteriorly and gliding. The veil collapses and is pulled inward and upward, and the stroke is repeated. Because the veil is incompletely webbed, the sea cucumber moves at an angle to its body axis.

FEEDING ECOLOGY AND DIET

The pelagic sea cucumber is a suspension feeder. It concentrates descending organic matter in mid-water by hanging vertically in the water column and spreading its extensive veil of webbed papillae into an inverted cone. Gut contents suggest that this species never ingests bottom sediment.

REPRODUCTIVE BIOLOGY

Spawning and a larval form have not been reported for the pelagic sea cucumber. Postlarval juveniles are pelagic and have midventral tube feet that are lost during growth. The ripe go-nad sometimes is visible through the body wall as a white or yellowish tuft.

CONSERVATION STATUS

Not listed by the IUCN or under the CITES convention.

SIGNIFICANCE TO HUMANS None known. ♦

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