''Psolus chitonoides'', also known as the slipper sea cucumber, armoured sea cucumber, creeping armoured sea cucumber, or creeping pedal sea cucumber, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

sea cucumber Sea cucumbers are echinoderms from the class (biology), class Holothuroidea ( ). They are benthic marine animals found on the sea floor worldwide, and the number of known holothuroid species worldwide is about 1,786, with the greatest number be ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Psolidae. It is found in shallow water on the western coast of North America. The scientific name "chitonoides" means resembling a

chiton Chitons () are marine molluscs of varying size in the class Polyplacophora ( ), formerly known as Amphineura. About 940 extant and 430 fossil species are recognized. They are also sometimes known as sea cradles or coat-of-mail shells or suck ...

Description

The slipper sea cucumber has an oval body some long and wide. The upper surface is domed and the under surface or sole is well-equipped with tube feet. A staggered row of large tube feet run along the centre of the sole, one or two rows of stout tube feet run on either side of this near the edge, and a single row of smaller feet set in pits run along the edges of the sole. The mouth, surrounded by a ring of tentacles is at one end of the animal. The tentacles are repeatedly branched and number eight to ten, either all the same size or with two smaller than the rest. The anus is on the dorsal surface on the opposite end to the mouth. The skin is leathery, somewhat spiny, and protected by rows of stiff, overlapping scales. The scales are yellow to bright orange and the tentacles are red with white tips.

Discovery

''Psolus chitonoides'' was discovered in 1886, in Puget Sound by Columbia University teams.

Distribution and habitat

The slipper sea cucumber is found on the western coast of North America, its range extending from the

Aleutian Islands The Aleutian Islands ( ; ; , "land of the Aleuts"; possibly from the Chukchi language, Chukchi ''aliat'', or "island")—also called the Aleut Islands, Aleutic Islands, or, before Alaska Purchase, 1867, the Catherine Archipelago—are a chain ...

Baja California Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northwesternmost of the 32 federal entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of B ...

. It occurs on both exposed coasts and in quiet inlets, in the

sublittoral zone The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminated ...

down to depths of about . Its soft, pliable sole means that it can stick to rocks and it is commonly found clinging firmly to vertical rock faces.

Ecology

The slipper sea cucumber is a

suspension feeder Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a spec ...

, intercepting particles floating past which are then trapped by sticky papillae on its feeding tentacles. It has a high concentration of

saponin Saponins (Latin ''sapon'', 'soap' + ''-in'', 'one of') are bitter-tasting, usually toxic plant-derived secondary metabolites. They are organic chemicals that become foamy when agitated in water and have high molecular weight. They are present ...

s in its tissues. This makes it toxic and it is avoided by most

predatory Predation is a biological interaction in which 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 ...

fish, gastropod molluscs and crabs; its flesh has been shown to be unpalatable to the tidepool sculpin (''Oligocottus maculosus''). Its main predators are

starfish Starfish or sea stars are Star polygon, star-shaped echinoderms belonging to the class (biology), class Asteroidea (). Common usage frequently finds these names being also applied to brittle star, ophiuroids, which are correctly referred to ...

, especially the

leather star The leather star (''Dermasterias imbricata'') is a starfish, sea star in the Family (biology), family Asteropseidae found at depths to off the western seaboard of North America. It was first species description, described to science by Adolph Ed ...

(''Dermasterias imbricata''). The juveniles of the species are photo negative. The eggs are a bright red in color.

References

{{Taxonbar, from=Q2367996 Dendrochirotida Animals described in 1901