''Psychropotes longicauda'' 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 ...

Psychropotidae Psychropotidae is a family of deep-sea swimming sea cucumbers. The geographic range of some psychropotids is very extensive at abyssal depths, whereas other species are found within more restricted ranges.P. A. Tyler & D. S. M. Billett (1988) The ...

. It inhabits the deep sea where the adult is found on the seabed. The larva is

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

and has an appendage shaped like a sail on its back which may enable it to move through the water. The animal is sometimes called the "gummy squirrel" because it looks like a

squirrel Squirrels are members of the family Sciuridae (), a family that includes small or medium-sized rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrel ...

-shaped

gummy bear Gummy bears (German: ''Gummibär'') are small, fruit gum candies, similar to a jelly baby in some English-speaking countries. The candy is roughly long and shaped in the form of a bear. The gummy bear is one of many gummies, popular gelat ...

Description

As an adult, ''Psychropotes longicauda'' has eighteen short feeding tentacles, each with a leathery terminal disc with retractile processes projecting around the margin. Its body is very flexible and can grow to a length of between . It is approximately cylindrical but broadest and somewhat flattened near the anterior end. At the posterior end there is a dorsal, tail-like appendage up to long, either pointed or with a pair of unequal-length tips. There is a double row of small

tube feet Tube or tubes may refer to: * Tube (2003 film), ''Tube'' (2003 film), a 2003 Korean film * "Tubes" (Peter Dale), performer on the Soccer AM#Tubes, Soccer AM television show * Tube (band), a Japanese rock band * Tube & Berger, the alias of dance/e ...

along the ventral surface and a single row of larger tube feet on each side of the body. The skin is soft and pliable and the colour is violet in preserved specimens. The larva has ten tentacles and is transparent with a reddish hue at the anterior end. It has an unpaired gelatinous dorsal appendage. Larvae can grow to at least in length excluding the appendage which may be nearly as long as the body.

Distribution and habitat

''Psychropotes longicauda'' is a

cosmopolitan Cosmopolitan may refer to: Internationalism * World citizen, one who eschews traditional geopolitical divisions derived from national citizenship * Cosmopolitanism, the idea that all of humanity belongs to a single moral community * Cosmopolitan ...

abyssal species of sea cucumber and is found on the seabed throughout the world's deep oceans. Its

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

and is often found more than above the ocean floor but still in the

abyssal zone The abyssal zone or abyssopelagic zone is a layer of the pelagic zone of the ocean. The word ''abyss'' comes from the Greek word (), meaning "bottomless". At depths of , this zone remains in perpetual darkness. It covers 83% of the total area ...

Behaviour

Adult ''Psychropotes longicauda'' are found on soft sediments through which they sift with the aid of their feeding tentacles. The eggs, with a diameter of , are the largest of any

echinoderm An echinoderm () is any animal of the phylum Echinodermata (), which includes starfish, brittle stars, sea urchins, sand dollars and sea cucumbers, as well as the sessile sea lilies or "stone lilies". While bilaterally symmetrical as ...

. The size of the eggs, and the fact that the larvae do not appear to feed, makes it so that the yolk nourishes them for an extended time and that they can therefore disperse widely.

References

{{Taxonbar, from=Q2068544 Psychropotidae Animals described in 1882