Holothuria forskali | |
---|---|
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Echinodermata |
Class: | Holothuroidea |
Order: | Aspidochirotida |
Family: | Holothuriidae |
Genus: | Holothuria |
Species: | H. forskali |
Binomial name | |
Holothuria forskali Delle Chiaje, 1823 |
|
Synonyms | |
|
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 Panningothuria by Rowe in 1969 and is the typetaxon of the subgenus.
Sea cucumbers are marine invertebrates and are closely related to the sea urchins and starfish. All these groups tend to be radially symmetric and have a water vascular system that operates by hydrostatic pressure, enabling them to move around by use of many suckers known as tube feet. Sea cucumbers are usually leathery, gherkin-shaped animals with a cluster of short tentacles at one end.
This sea cucumber has a cylindrical body and can grow to thirty centimetres long. It is usually deep brown or black but sometimes has an underlying yellowish mottling, especially on the underside. The skin is soft yet coarse and tough and is covered with fleshy papillae which are often tipped with white. The papillae are believed to be sensory organs sensitive to touch and possibly to chemicals dissolved in the water. The underside has three rows of tube feet for walking and climbing while the upper side has two rows of rudimentary suckers. The anterior end has a bunch of twenty yellowish short, retractable tentacles encircling the mouth. At the posterior, inside the body cavity, there are a bundle of Cuvierian tubules or cotton glands which can be ejected as a tangle of sticky white threads to confuse or enmesh predators.
The black sea cucumber occurs around the Atlantic coasts of northwest Europe, the Canary Islands, the Azores and in the Mediterranean Sea. It is found on boulders and rocks, particularly vertical surfaces, from the intertidal zone down to a depth of about fifty metres.