Holothuria tubulosa, the
cotton-spinner or
tubular sea cucumber, is a
species of
sea cucumber in the
familyHolothuriidae. It is the
type species of the
genusHolothuria and is placed in the subgenus
Holothuria, making its full name
Holothuria (Holothuria) tubulosa.
[2]
Description
Holothuria tubulosa grows to a length of between 20 centimetres (7.9 in) and 45 centimetres (18 in), and a diameter of 6 centimetres (2.4 in). It is roughly cylindrical with a flattened base on which there are three longitudinal rows of tube feet. It has a tough, leathery skin. The general colour is a shade of brown and the surface is covered with numerous dark-coloured, conical, thorn-like projections known as papillae. It often appears greyish, as it secretes a protective film of
mucus to which bits of
seaweed and sediment may adhere. It has a fringe of short, flattened
tentacles around the mouth at the anterior end and an anus at the posterior end.
[3][4]
Distribution and habitat
Holothuria tubulosa is found in temperate regions of the eastern
Atlantic Ocean as far north as the
Bay of Biscay, in the
Mediterranean Sea, where it is abundant. It is found on sandy
seabeds, among seagrass (
Posidonia spp.) and on muddy rocks to a depth of about 100 metres (330 ft).
[2][3]Biology
Male
Holothuria tubulosa releasing sperm
Holothuria tubulosa feeds on detritus, algae and plankton.
[5] It uses its tube feet to move across the surface or adhere to rocks.
[3]Holothuria tubulosa is
dioecious, with each individual being either male or female but with no difference between them in external appearance. In a study in the Mediterranean Sea, a mass spawning event was observed in the afternoons of the two days in August 2003 that coincided with the
full moon. Large numbers of mature individuals simultaneously adopted the spawning position, rearing their anterior ends up and leaving only the hind third of their body in contact with the seabed. This raises their genital orifices, situated just below the mouth, clear of the substrate to allow for maximum dispersal of the
gametes. First, some individuals, believed to be males, emitted a whitish fluid which gradually dispersed in the surrounding water. Next, a smaller number of individuals, believed to be female, emitted a more viscous fluid, perhaps in response to the release of the male gametes. Each release lasted about 30 minutes. The necessary conditions for spawning seemed to be a full moon and a sea temperature of about 25 °C (77 °F).
[4]
The fertilised eggs hatch in about 24 hours and the developing larvae are planktonic. They feed on microscopic algae and pass through several stages over the course of a few weeks before settling on the seabed and undergoing metamorphosis into juveniles.[6]
Uses
Sea cucumbers are used for food in some countries, particularly Taiwan, Hong Kong, Singapore, Korea and Norway. There is a commercial fishery in Turkey and a closed season is imposed in August and September to allow the animals to spawn. Holothuria tubulosa is one of the species collected by divers, who can gather 2000 to 3000 in a day. The sea cucumbers are either sun dried, oven dried, or frozen before being exported.[7]
References
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^Samyn, Y. (2010). "Holothuria tubulosa". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 29 October 2016..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"""""'"'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}
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^ abcdPaulay, Gustav (2010). "Holothuria (Holothuria) tubulosa Gmelin, 1791". World Register of Marine Species. Retrieved 2012-01-15.
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^ abcHolothuria tubulosa EuropeanMarineLife. Retrieved 2012-01-15.
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^ abOcana, A. & L. Sanchez Tocino (2005). "Spawning of Holothuria tubulosa (Holothurioidea, Echinodermata) in the Alboran Sea (Mediterranean Sea)"(PDF). Zoologica Baetica. 16: 147–150.
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^Sea cucumber
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^Sea cucumber culture Brief introduction to mariculture of five selected species in China. Retrieved 2012-01-16.
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^The commercial sea cucumber fishery in Turkey Beche-de-Mer Information Bulletin. Retrieved 2012-01-16.