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Related to Holothurians: Holothuroidea, Sea cucumbers



(sea cucumbers), a class of invertebrates (Holothurioidea) of phylum Echinodermata.

The skeleton of the holothurians is greatly reduced. The body is pentactinally symmetrical, which is characteristic of the phylum in general, but in the holothurians it is marked by the biliterally symmetrical arrangement of many of the organs. The largest holothurians reach 2 m in length. The body is vermiform, with a mouth at one end and an anal opening at the other. The mouth, surrounded by a crown of tentacles that serve to capture the food, leads into a long tubular gut. Respiration is accomplished by an ambulacral system and a so-called respiratory tree—branched sacs leading to the rectum. Holothurians develop by metamorphosis; free-swimming larvae hatch from the eggs. There are some 1,100 species.

The holothurians are exclusively marine, benthic, sluggish, creeping animals, feeding on sediment or tiny plankton. When greatly irritated they are capable of self-mutilation (au-totomy), but the lost organs readily regenerate. In China the sea cucumber is dried and used as food. The animals (particularly the trepang) are also of some commercial importance in the USSR, in the Far East.


Dogel’, V. A. Zoologiia bespozvonochnykh, 5th ed. Moscow, 1959.
Bol’shoi praktikum po zoologii bespozvonochnykh, part 2. Moscow, 1946.
Zhizn’ zhivotnykh, vol. 2. Moscow, 1968.
References in periodicals archive ?
Efficacy of chemical markers and physical tags for large-scale release of an exploited holothurian.
Aspects of the reproductive and larval biology and ecology of the temperate Holothurian Stichopus mollis (Hutton).
Tropical fisheries are traditionally based on several holothurians (Fig.
In the meantime, assessments of the residual resource left behind after fishing and of the recovery rate of holothurian populations are being conducted by fishery biologists.
Holothurian fisheries are based on a few deposit-feeding species belonging to two families and five genera: Actinopyga and Holothuria (Holothuridae) and Parastichopus, Stichopus, and Thelenota (Stichopodidae).
This resulted in a rapid change in the holothurian species being exploited, from first-category species (i.
Access to the statistics at the various levels shown in Figure 3 and their reliability is considered in order to present some conclusions and recommendations for further assessment and management of holothurian resources.