#holothuroidea

Swimming Sea Cucumber aka Headless Chicken Monster (Enypniastes eximia), family Pelagothuriidae, order Elasipodida

Unlike most sea cucumbers, which are benthic (bottom dwelling), this species swims through the water column (nektonic).

Protankyra bidentata

A sea cucumber from the Pacific and Indian Oceans.

at night these secretive fat 'cumbers like to gather at the sea floor to discuss beer prices, strange car advertisements and other cucumber things

while they may look like delicious plump fruit, I advise you not to touch them or look at them funny as they are very shy and neurotic and will secrete a horrible poison that'll probably make you very sick

glorpiness rating: sea apple? where?

Atelostomata. This superorder of sea urchins are irregularily-shaped and lack a feeding lantern (they have cilia rather than calcium carbonate teeth). Members include the heart urchins

Holothuroidea. This class is made up of sea cucumbers, sea floor creatures with leathery skin and an elongated body.

A Striking Salad of Sea Cumbers

No, they’re not a vegetable-- sea cucmbers make up the class Holothuroidea, which is a member of the echinoderm family-- invertebrates which also include star fish, sea urchins, and sand dollars. There are about 1,700 species of sea cucumber found on the ocean floor, in open water, and in coral reefs. These invertebrates are found all over the world, but the greatest variety of species can be found in the Asian Pacific, in reefs around Southeast Asia, Indonesia, and eastern Australia.

While they are invertebrates, sea cucumbers do have an internal skeleton: a structure made of tiny calcified branches called ossicles that are joined throughout the skin by connective tissue. Some species enlarge their ossicles to form hard plates, which can protect them from predators. Outside this common feature, sea cucumbers can take many forms. The stereotypical sea cucumber has a cylindrical body, often with bumps that resemble warts. These bumps have important functions ranging from locomotion to feeding, and in some species the bumps are elongated into tentacles. Most species also posses five pairs of tube-like feet. Outside the stereotype, however, members of the Holothuroidea class can take many forms, ranging from perfectly round to worm-like, and with many variations on appendages, location, and predatory defense. The average sea cucumber species range from  10 to 30 cm (4 to 12 in), but again there are many exceptions to the rule.

Holothuroidea has a relatively simple anatomy: a mouth, leading either to a stomach or the intestines, which empty into the anus. The anus is also used to filter oxygen from the surrounding water. As a defense mechanism, sea cucumbers may expel their organs through their anus when startled, and regrow them later. Other discharge a sticky mucus that ensnares predators. Many are toxic, and use bright colors and large appendages to warn potential predators away. However, some fish such as pufferfish, crustaceans, and large mollusks, have been known to make a meal of sea cucumbers when few alternatives are available. In turn, sea cucumbers feast on debris, plankton, and decaying organic matter. Most do this on the ocean floor, but some are able to swim or even ‘jump’ up to 1000m before floating slowly back down.

Like most echinoderms, sea cucumbers are not social; they largely ignore each other when they happen to occupy the same space. Different species can reproduce sexually, asexually, or both, and do so throughout the year. Most simply release thousands of sperm or ova into the open water, and these drift through the ocean until they combine to make a fertilized egg. The egg takes only three days to develop into a free-swimming larvae called the auricularia stage. Next is the doliolaria stage, in which the body enlongates and settles on or near the ocean floor. The last stage is the pentacularia, in which tentacles and tube-feet emerge. Once these features have finished growing, usually in a few months to a year, the sea cucumber are ready to reproduce. 

Conservation status: Because of the large number and distribution of sea cucumber species, their status ranges from Not Threatened to Endangered. Their primary threat is over-harvesting for medicine or food. Many species on coral reefs are also threatened by habitat loss.

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Photos

White teatfish sea cucumber (Holothuria fuscogilva) by Steve Purcell

California sea cucumber (Parastichopus californicus) by Gerald and Buff Corsi

Transparent sea cucumber (Pelagothuria natatrix) by Larry Madin

Chocolate chip sea cucumber (Isostichopus badionotus) by NOAA

Leopard sea cucumber (Bohadschia argus) by Leonard Marks

Fotos de la práctica de Equinodermos en Animales I. Me gusta este filo, aunque en laboratorio no tenían un representante de los pepinos de mar (Holothuroidea).

Dos imágenes superiores: galleta de mar y pan de muerto de mar jaja, clase Equinoidea, misma que la de los erizos de mar.

Imagen del medio: lirio de mar, clase Crinoidea.

Inferior izquierda: se parecen un poco a las estrellas de mar pero sus brazos son más alargados, clase Ophiuroidea.