Cuvierian tubules are clusters of fine tubes located at the base of the respiratory tree in some

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 ...

s in the

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

'' Bohadschia'', ''

Holothuria ''Holothuria'' is the type genus of the marine animal family Holothuriidae, part of the class Holothuroidea, commonly known as sea cucumbers. Members of the genus are found in coastal waters in tropical and temperate regions. They are soft bodied ...

'' and '' Pearsonothuria'', all of which are included in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Holothuriidae Holothuriidae is a family of sea cucumbers, a type of echinoderm. Description Members of the family Holothuriidae have thick fleshy bodies and several rows of tube feet which are used for moving around and for adhering to the surface. The body ...

. The tubules can be discharged through the anus when the sea cucumber is stressed. They lengthen when they come into contact with seawater and become adhesive when they encounter objects so that they function as a defence against potential

predators Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

. They are named after the French zoologist

Georges Cuvier Jean Léopold Nicolas Frédéric, Baron Cuvier (; 23 August 1769 – 13 May 1832), known as Georges Cuvier, was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuvier ...

, who first described them.

Mode of action

There may be several hundred Cuvierian tubules which are attached to the left respiratory tree and lie freely in the coelomic fluid in the body cavity. When stressed, the sea cucumber faces away from the attacker and contracts its body wall muscles sharply. This causes the wall of the

cloaca In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles and birds, a ...

to tear and the anus to gape and the free ends of some of the tubes to be ejected. Water from the respiratory tree is forced into these tubules causing a rapid expansion and they elongate by up to 20 times their original length. They have great tensile strength and become sticky when they encounter any object. The adhesive is unique among marine invertebrates and a firm grip is obtained in under ten seconds. The mass of threads can entangle and immobilize potential predators such as small

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...

s. The threads become detached from the sea cucumber which crawls away. The tubules are readily regenerated, a process that takes about 17 days in ''

Holothuria leucospilota ''Holothuria leucospilota'', commonly known as the black sea cucumber or black tarzan, is a species of marine invertebrate in the family Holothuriidae. It is placed in the subgenus ''Mertensiothuria'' making its full scientific name ''Holothuria ...

'' and five weeks in ''

Holothuria forskali ''Holothuria forskali'', the black sea cucumber or cotton-spinner, is a species of sea cucumber in the family Holothuriidae. It is found at shallow depths in the eastern Atlantic Ocean and the Mediterranean Sea. It was placed in the subgenus ''Pa ...

''. The tubules contain a toxic

saponin Saponins (Latin "sapon", soap + "-in", one of), also selectively referred to as triterpene glycosides, are bitter-tasting usually toxic plant-derived organic chemicals that have a foamy quality when agitated in water. They are widely distributed ...

called

holothurin The holothurins are a group of toxins originally isolated from the sea cucumber '' Actinopyga agassizii''. They are contained within clusters of sticky threads called Cuvierian tubules which are expelled from the sea cucumber as a mode of sel ...

, which is also present in the body wall in some sea cucumber species. Image:Ashy pink sea cucumber (Holothuria fuscocinerea).jpg, ''

Holothuria fuscocinerea ''Holothuria fuscocinerea'', the ashy pink sea cucumber, is a species of sea cucumber in the family Holothuriidae. It is placed in the subgenus ''Stauropora'', making its full name ''Holothuria'' (''Stauropora'') ''fuscocinerea''. It is native to ...

'' Image:Tubes de Cuvier émis par Holothuria pervicax.jpg, ''

Holothuria pervicax ''Holothuria pervicax'' is a species of sea cucumber in the genus ''Holothuria''. It is commonly called the stubborn sea cucumber due to its inability to be kept alive in captivity. It is commonly found buried beneath rocks on reefs in warm water ...

'' Image:Holothuria sanctori Cuvieran Tubes.jpg, ''

Holothuria sanctori ''Holothuria sanctori'' is a species of sea cucumber in the genus ''Holothuria ''Holothuria'' is the type genus of the marine animal family Holothuriidae, part of the class Holothuroidea, commonly known as sea cucumbers. Members of the genus ...

'' Image:Holothuria-Maldives.jpg, ''

Bohadschia vitiensis ''Bohadschia vitiensis'' is a species of sea cucumber in the family Holothuriidae. It is also known as the brown sandfish and brown sea cucumber. It is widespread in shallow waters of the Indo-Pacific. It appears to be able to hybridize with ''Bo ...

'' held in hand out of the water Image:Holothuria forskali Rab2011 h 3798.JPG, ''

References

Echinoderm anatomy {{echinoderm-anatomy-stub

Mode of action

See also

References