''Thyone fusus'' 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 the seabed in the northeastern Atlantic Ocean and the Mediterranean Sea. It is a suspension feeder and catches food particles floating past with its branching feeding tentacles.

Description

''Thyone fusus'' has an oval body up to long. The anterior (front) end has a mouth surrounded by a circle of ten branching tentacles while the posterior (back) end bears the

anus The anus (Latin, 'ring' or 'circle') is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, the residual semi-solid waste that remains after food digestion, which, d ...

and is bluntly rounded. There are a few tube feet, and these may be arranged in longitudinal rows. The skin is smooth and fine with few calcareous spicules; these spicules are usually table-shaped, with four holes and a pair of fused rods making a spire, and may also be present in the tube feet. The colour of this sea cucumber is usually some shade of brown, pink or white.

Distribution and habitat

''Thyone fusus'' is found in the northeastern Atlantic Ocean and the Mediterranean Sea, its range extending from Norway southwards to

Madeira ) , anthem = ( en, "Anthem of the Autonomous Region of Madeira") , song_type = Regional anthem , image_map=EU-Portugal_with_Madeira_circled.svg , map_alt=Location of Madeira , map_caption=Location of Madeira , subdivision_type=Sovereign st ...

. In the British Isles it is present from the Shetland Isles southwards along the east coast of Scotland to Northumberland. Its depth range is from . It is found in sheltered positions on shelly and muddy seabeds where it lies buried with just the tentacles and anterior end exposed.

Ecology

''Thyone fusus'' is a

suspension feeder Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...

, consuming

diatom A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising sev ...

s, single-cell algae and drifting organic particles, as well as zooplankton such as

copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (inhabiting sea waters), some are benthos, benthic (living on the ocean floor) ...

s, ostracods,

protozoa Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Histo ...

ns,

nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...

s, jellyfish and larvae. The two ventral feeding tentacles are much shorter than the others and have forked ends. Each large tentacle in turn shrinks and folds and is pushed into the mouth. A small tentacle is held close to the mouth and cooperates with each of the others by scraping off any food particles that are still adhering to the large one when it is withdrawn from the mouth. On the western coast of Ireland, these sea cucumbers bury themselves in the sediment between October and February and go into a form of

hibernation Hibernation is a state of minimal activity and metabolic depression undergone by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It most ...

. They do not feed during this time and their body wall condition deteriorates, but the gonads continue developing, and spawning takes place in early spring.

References

{{Taxonbar, from=Q2490549 Phyllophoridae Fauna of the Atlantic Ocean Fauna of the Mediterranean Sea Animals described in 1776 Taxa named by Otto Friedrich Müller