Sorberaceans: Sorberacea

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Sorberaceans (soor-buh-RAY-shuns) are a small group of deep-water, bottom-dwelling sea animals related to sea squirts. Some species of sorberaceans have an egg-shaped body, and others are slightly longer than egg-shaped. The outside layer of sorberaceans is covered with short hairlike fibers and with the shells of tiny animals, sand, and mud particles sticking to the fibers. Sorberaceans are 0.1 to 2.4 inches (0.3 to 6.0 centimeters) long. Water intake and outflow openings are on opposite ends of the body and are directed away from each other. The outflow opening is very small. The intake opening is large, is on the front end or the side of the body, and is surrounded by six rounded bulges. The intake opening leads to the mouth cavity, which is lined with the same layer that covers the body. The mouth cavity leads into a small chamber lined with slits and has a few openings that lead to a system of thin-walled tubes that open into a second chamber. Some species of sorberaceans have a very large stomach, which occupies most of the inside of the animal. All species have a kidney.


Sorberaceans live in all the oceans of the world but have not been found in the northernmost waters of the Arctic Ocean or the northern part of the Pacific Ocean.


Sorberaceans live at the bottom of the deepest part of the ocean, although some have been found in shallower water. The deep bottom is almost always soft and covered by a thick layer of mud, on which sorberaceans live unattached.


Sorberaceans probably eat small moving invertebrates (in-VER-teh-brehts), or animals without a backbone.


Sorberaceans do not survive capture, and scientists have not directly observed their behavior. They do know that sorberaceans live alone rather than in colonies. Although they are not firmly attached to the bottom, it is unlikely that these animals move. The hairlike fibers covering the body are encased in attached particles of mud and shells. This evidence suggests that the animals are anchored in the mud and cannot actively move.

Scientists believe sorberaceans actively search and capture prey using their muscular water-intake opening. The fingerlike bulges on the end of the opening may work as a hand for capturing small invertebrates.

Sorberaceans make both eggs and sperm. The eggs are laid and develop outside the parent's body. Other than that, scientists do not know how sorberaceans reproduce. The larvae have never been found. The youngest sorberaceans found already had the adult form. Larvae (LAR-vee) are animals in an early stage that change form before becoming adults.


Sorberaceans have no known importance to people.


Sorberaceans are not considered threatened or endangered.


Physical characteristics: Oligotrema sandersi sorberaceans are no longer than 0.2 inches (5 millimeters). The oval body is covered by sparse hairlike fibers with attached mud particles and the shells of tiny animals. The intake and outflow openings are on opposite sides of the body. The intake opening is very muscular, turns inside out, and has six fingerlike bulges. The stomach is very large and occupies most of the animal's body.

Geographic range: Oligotrema sandersi (abbreviated to O. sandersi) sorberaceans live in the Atlantic Ocean.

Habitat: O. sandersi sorberaceans live in the deepest part of the ocean.

Diet: O. sandersi sorberaceans eat small invertebrates.

Behavior and reproduction: Scientists do not know how O. sandersi sorberaceans behave or reproduce.

Oligotrema sandersi and people: O. sandersi sorberaceans have no known importance to people.

Conservation status: O. sandersi sorberaceans are not considered threatened or endangered. ∎



Brusca, Richard C., Gary J. Brusca, and Nancy Haver. Invertebrates. 2nd ed. Sunderland, MA: Sinauer, 2002.

Gage, John D., and Paul A. Tyler. Deep-Sea Biology. New York: Cambridge University Press, 1991.