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 holothurian species worldwide is about 1,717 with the greatest number being in the Asia Pacific region. Many of these are gathered for human consumption and some species are cultivated in aquaculture systems. The harvested product is variously referred to as trepang, namako, bêche-de-mer or balate. Sea cucumbers serve a useful role in the marine ecosystem as they help recycle nutrients, breaking down detritus and other organic matter after which bacteria can continue the degradation process.
Brittle stars or ophiuroids are echinoderms in the class Ophiuroidea closely related to starfish. They crawl across the sea floor using their flexible arms for locomotion. The ophiuroids generally have five long, slender, whip-like arms which may reach up to 60 cm (24 in) in length on the largest specimens. They are also known as serpent stars; the New Latin class name Ophiuroidea is derived from the Ancient Greek ὄφις, meaning "serpent".
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, limbless invertebrates that dwell on the ocean floor and are usually detritivore. They resemble a cucumber in form. The genus contains some species that are harvested and sold as food.
The Asterinidae are a large family of sea stars in the order Valvatida.
The Brisingids are deep-sea-dwelling starfish in the order Brisingida.
Enypniastes is a genus of deep-sea sea cucumber. Due to its unique appearance, the genus has been dubbed the headless chicken fish, headless chicken monster, and the Spanish dancer. It is also known as the swimming sea cucumber, and some are called the pink see-through fantasia.
Synaptidae is a family of sea cucumbers that have no tube feet, tentacle ampullae, retractor muscles, respiratory trees, or cuvierian tubules. They also lack radial canals of the water-vascular system, with only the circumoral ring present.
Cucumariidae is a family of sea cucumbers, marine animals with elongated bodies, leathery skins and tentacles that are found on the sea bed.
Clypeaster, common name "cake urchins" or "sea biscuits", is a genus of echinoderms belonging to the family Clypeasteridae.
Aquilonastra is a genus of small sea stars within the family Asterinidae. It has over 20 described species.
Chiridotidae is a family of sea cucumbers.
Elpidia is a genus of deep-sea sea cucumbers. Members are characterised by their rod-shaped spicules which each have two pairs of obliquely-placed horizontal arms and two vertical apophyses. There is a high degree of endemism in this genus with different species occupying different deep sea basins or regions.
Myriotrochidae is a family of sea cucumbers.
Ophiactis is a genus of brittle stars (Ophiuroidea).
Ophiomusium is a genus of brittle stars.
Hemisphaeranthos is an extinct genus of sea cucumbers. The following species are recognised in the genus Hemisphaeranthos:
Chiridota is a genus of sea cucumbers in the family Chiridotidae. It is an extant genus but some fossil species are known.
Psolus is a genus of sea cucumbers in the family Psolidae, marine animals with long bodies, leathery skins and tentacles, that inhabit the sea bed.
Trachythyone is a genus of sea cucumbers in the family Cucumariidae.
Thyone is a genus of sea cucumbers in the family Phyllophoridae.
