Sea Cucumber

“Soft, muddy substrates, often associated with seagrass beds” (Hendler, Miller, Pawson, Kier 269)

“Nova Scotia, southward along the eastern seaboard of the United States and around the Gulf of Mexico coastline to Texas. It is also reported from Venezuela (Martinez 1991b). In southern Florida, it has been found in Biscayne Bay and off Key West. Depth: Previously reported from 0 to 66 m (217 ft); a museum (USNM) specimen from off Georgia was collected at 183 m (600 ft) (Miller, previously unpublished)” (Hendler, Miller, Pawson, Kier 269)

“This is a medium-sized sea cucumber that can reach a length of 12-15 cm (5-6 in). The body is stout and robust, swollen near the middle, and gently tapered at each end. Generally the mouth and anus are curved slightly upward. Specimens excavated from soft sediment contort their bodies into a spherical shape about the size of a golf ball by bringing mouth and anus into close proximity. The body wall is thin and very soft, because of the small number of skeletal ossicles and the numerous hairlike tube feet scattered over the entire body. The tube feet are cylindrical, though somewhat tapered near their sucking disks, and they are longest and most numerous on the ventral surface. The mouth is surrounded by eight large and bushy tentacles and two ventral tentacles about one-fourth the size of their neighbors. The anus is surrounded by five large, triangular, radial teeth, each of which is overlain by two pairs of papillae, the inner pair twice the length of the outer pair. The number of ossicles is greatly reduced in large, old individuals, although some usually remain in the feet or in the body wall surrounding the mouth and anus. The body wall ossicles are tables with a flat, squarish disk; in the feet the tables have an elongate curved disk. Both types of tables have tall spires composed of four pillars. In life, S. briareus is green or brown, although some individuals appear to be almost black. Usually, conspicuous darker patches of pigment cover the mouth and anus and are especially noticeable when the body wall is contracted into a spherical shape. In some individuals, the tube feet are brownish orange. The introvert is gray to black, the tentacle stems black, and the tentacle branches gray” (Hendler, Miller, Pawson, Kier 269)

Sclerodactyla briareus adults bury themselves in the sediment at the ocean floor, leaving only the mouth and anus protruding into the open water. During winter in colder climes, it withdraws more fully into the ocean floor and hibernates. It will also withdraw temporarily in response to the removal of a light source. It will rise from the sediment and expose more of its body in response to diminishing oxygen concentrations. S. briareus is able to tolerate lower salinity water conditions better than most echinoderms, allowing it to survive in brackish environments. It also has impressive tolerance of hypoxic conditions, demonstrating the ability to survive them for over two days at a time. S. briareus exhibits selective feeding behavior, eating significant amounts of organic detritus, as well as the ability to directly absorb free amino acids from the water. In areas where S. briareus is particularly abundant, large numbers of this species may be washed ashore by violent storms. Like many sea cucumbers, S. briareus resorts to autotomy of its internal organs and the forward sections of its body as a defensive mechanism. Autotomy can also be induced by fouled or toxic water. The unsavory nature of its tissues, particularly the skin and genitals, is a further protective measure against predators.

Sclerodactyla briareus is a burrowing sea cucumber of medium size found in the North Atlantic and off the coast of Venezuela. Adults reach lengths of 12 to 15 cm. The body is dark green or brown in color, with some individuals so dark as to appear almost black. The introvert (frontal area, including tentacles, that can be withdrawn into the body) and tentacle branches are gray, while the tentacle stems are black. The body is thick throughout its whole length with an especially swollen middle. Both ends curve slightly upwards. S. briareus is a sturdy species, able to survive in brackish waters that have too low of a salinity level for most other echinoderms. It can survive extended periods of hypoxia as well. When threatened, S. briareus can eject its internal organs in order to tangle and confuse predators.