Cuvierian tubules

Cuvierian tubules are clusters of fine tubes located at the base of the respiratory tree in some sea cucumbers in the genera Bohadschia, Holothuria and Pearsonothuria, all of which are included in the family Holothuriidae.

They lengthen when they come into contact with seawater and become adhesive when they encounter objects, functioning as a form of defense against predators or sources of danger.

[1] 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.

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.

[2] The tubules contain a toxic saponin called holothurin, which is also present in the body wall in some sea cucumber species.