''Thyone roscovita'' is a species of

sea cucumber Sea cucumbers are echinoderms from the class Holothuroidea (). They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. The number of holothuria ...

in the family

Phyllophoridae Phyllophoridae is a family of sea cucumbers, marine invertebrates with elongated bodies, leathery skins and feeding tentacles. Members of the family are characterised by a complex ring of calcareous ossicles arranged in a tube, making a mosaic ...

. It is found on gravel, sand and mud substrates in the north-eastern Atlantic Ocean and the Mediterranean Sea at depths down to about . It is a suspension feeder and catches food particles floating past with its branched feeding tentacles.

Description

''Thyone roscovita'' has a cylindrical body up to long. The general colour is pinkish-grey or pinkish-brown, with scattered darker brown and opaque spots. The body has a thick cuticle, and is densely covered with yellowish, flat-topped tube feet. The anterior (front) end has a mouth surrounded by a ring of ten branching tentacles, and the plume of tentacles is often the only part of the animal visible, the body being buried in the sediment. The tentacular plume is up to long; the bases of the tentacles are thick and whitish, the secondary branches are black and needle-like, and these bear transparent wispy filaments that give a vaporous effect.

Distribution and habitat

''Thyone roscovita'' is native to the north-eastern Atlantic Ocean, the North Sea, the English Channel and the Mediterranean Sea. Its range extends from the Shetland Isles and the coasts of Britain and Ireland to the

Bay of Biscay The Bay of Biscay (), known in Spain as the Gulf of Biscay ( es, Golfo de Vizcaya, eu, Bizkaiko Golkoa), and in France and some border regions as the Gulf of Gascony (french: Golfe de Gascogne, oc, Golf de Gasconha, br, Pleg-mor Gwaskogn), ...

and the western Mediterranean Sea. It is found semi-buried in the sediment on soft bottoms, such as gravel, shelly sand or mud, from the

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...

down to about . Less frequently, it tucks itself into a rock crevice, with just its tentacles projecting.

Ecology

''Thyone roscovita'' unfurls its oral tentacles and uses them to catch organic particles floating past. The smallest branches have adhesive papillae to which the particles stick. The tentacles are retracted in a predetermined order to transfer any food caught to the mouth. The sexes are separate in this species. The gametes are liberated into the water column where fertilisation takes place. The barrel-shaped larvae have a short planktonic life before sinking to the seabed and undergoing

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...

into juvenile sea cucumbers.

References

{{Taxonbar, from=Q2379571 Phyllophoridae Echinoderms of the Atlantic Ocean Fauna of the Mediterranean Sea Animals described in 1889