Trachythyone elongata

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Geographic Range

This species can be found in the waters of the Mediterranean and the Atlantic from Norway to Morocco. (Grzimek 1972)

Habitat

This species is strictly marine and can be found in the sand and mud from sea level to 110 meters in the water. (Grzimek 1972.)

Physical Description

This species has an elongated body that is usually U-shaped and resembles the shape and size of the vegetable, cucumber, where it gets its name. It has a tube-shaped ventral surface with 5 rows of tube feet that extend the entire length of the body. It does not have arms. (Banister and Campbell 1985.) The dorsal surface is covered with stiff, conical projections that are brownish or gray in color. The body wall is naked with only minutely defined ossicles and is very elastic and leathery in texture. Their mouth is located at the anterior and their anus is located at the posterior. The mouth is surrounded by a ring of simple branched tentacles that are usually retractable when they catch their prey. (Grzimek 1972.) They have a water vascular system that includes a water ring around a proximal pharnyx with 5 radial canals that run the length of the body wall. They are pentameral, or have 5-rayed symmetry with 5 rows of tube feet.(Fisheries and Oceans Canada). They range in size from a few centimeters to 8 inches. (Carson 1955)

Reproduction

They mainly reproduce by sexual reproduction and have only one gonad which is a cluster or tuft of closed tubules. Spawning lasts about 30 minutes and is done directly in the surrounding water usually in late afternoon. The male gamete is released first into the water then the females lay eggs. Gamete-release is triggered by the presence of pheromones. Fertilization thus takes place in the water, then the fertilized egg either sinks to the bottom or rises to the water surface. (Grzimek 1972.)

Behavior

Movement is very slow and is like that of an earthworm crawling along the ocean floor. When they are attacked by predators, mainly sea stars, they respond violently by arching back and forth in defense. This is one of the only times that they move faster than a crawl. (Stachowitsch 1992.)

Food Habits

They will eat almost anything in range but usually eat plankton and other small microscopic organisms (Stachowitsch 1992). They function like earthworms, ingesting sand and mud along with the plankton and pass it through their bodies (Carson 1955). Some species of sea cucumbers have annual periods of dormancy where they eat nothing at all and only eat when the water has reached a certain temperature. During these rest periods that usually start in October or November, they display atrophy of their internal organs. New internal organ are then regenerated when they are ready to eat again, about 6 weeks later (Grzimek 1972).

Economic Importance for Humans: Positive

Sea cucumbers can be used in home saltwater aquariums to keep them clean of plankton and other unwanted small organisms.

Sea cucumbers are also important to the fishing industry, especially pepineros (sea cucumber fishermen) because they are a prized ingredient in Asian cuisine.

Sea cucumbers are first gutted, their body wall dried, and then made into a soup (Detjen 1993).

In addition, scientists say that studying the methods that sea cucumbers use to deal with infections may yield information about peritonitis in humans. (Stutz 1995.)

Economic Importance for Humans: Negative

No major negative effects known, but if sewage is dumped into waters it may settle all of the way on the ocean floor. Such contaminates may be ingested by the sea cucumber and eventually affect organisms higher on the food chain. (Detjen 1993.)

Conservation Status

All fishermen must possess a special license to fish sea cucumbers and some coastal areas have closed fishing of sea cucumbers and restricted it to certain times of the year in order to protect the species. (Stutz 1995.)

Contributors

Ashlea Rives (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

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coastal

the nearshore aquatic habitats near a coast, or shoreline.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

native range

the area in which the animal is naturally found, the region in which it is endemic.

References

Banister, K., A. Campbell. 1985. The Encyclopedia of Aquatic Life. New York City: Facts on File, Inc..

Carson, R. 1955. The Edge of the Sea. Boston: Houghton-Mifflin.

Detjen, .. 1993. Sludge Site off N.J. Fouls Sea's Food Chain. Underwater USA, Jan. 1993.

Fisheries and Oceans Canada, "Sea Cucumbers" (On-line). Accessed February 15, 2000 at http://www.ncr.dfo.ca.

Grzimek, M. 1972. Grzimek's Animal Life Encyclopedia, Vol. 3: Mollusks and Echinoderms. New York: Reinhold and Van Nostrand.

Stachowitsch, .. 1992. The Invertebrates: An Illustrated Glossary. New York: Wiley-Liss.

Stutz, .. 1995. The Sea Cucumber War. Audubon, Vol. 97: 16+.