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Out of context: Reply #30232
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Sea cucumbers belong to a group of echinoderms called holothurians. They are sluggish, tube-shaped, bottom dwelling animals that are found worldwide. There are several species of holothurians in the Gulf of Maine but the one most commonly found nearshore, Cucumaria frondosa, is the subject of this new fishery.
C. frondosa is a cold water animal found along the western Atlantic coast from Greenland to the northern shore of Cape Cod. In the Gulf of Maine it can be one of the most abundant benthic animals found over rocky bottoms and in some local areas may account for 50% of the benthic biomass. It is most common in depths of less than 100 feet of water and it prefers to cling to hard surfaces, but can be found in coarse gravel or shell debris.
C. frondosa does look very much like a cucumber (Figure 1). It has a long, cylindrical body with greenish to brownish, leathery skin and five rows of tube feet which are used for locomotion and attachment. At one end is a mouth with a circle of branching tentacles and at the other an anal opening. The animal lays on its side so the ventral side, which comes in contact with the bottom, has well developed tube feet for attachment, while on the dorsal side the tube feet are less developed. The body is extremely flexible and can be tightened into a knot when stressed or loosened into a long tube when relaxed. The relaxed bodies of larger individuals may reach almost 20 inches.
The internal organs of the cucumber lay within the tube-like body chamber surrounded by the skin and a layer of longitudinal muscle bands. It is the skin and muscle bands that are the edible part of the animal. The internal organs consist of the digestive system for food processing, the gonad for reproduction, the respiratory trees for the removal of oxygen from the water, and a nerve ring that directs the operation of the muscles and tentacles. The cucumber is capable of eviscerating (casting off) its internal body organs during times of stress which can later be regenerated.
The sea cucumber is a non-selective suspension feeder, taking its food indiscriminately from the surrounding water. The small bits of detritus and microscopic organisms that are floating just above the bottom are trapped by the cucumber's tentacles. There are ten tentacles that are covered with a sticky mucous and are extended in the water until they are filled with food particles. One at a time the tentacles are then placed in the mouth opening where the food material is scraped off. When feeding, the animal always orients itself into the prevailing water current in order to take full advantage of the available food supply.
The sexes are separate, but microscopic examination of the gonad is the only reliable way to distinguish males from females. The gonad is located along one side of the body cavity and begins to produce eggs or sperm in the fall for the next spring's spawning season. Spawning occurs from about late March to mid-April and coincides with the spring plankton bloom. At this time the eggs and sperm are released into the water column where the eggs are fertilized and develop into a brief larval stage, at which time the animals are bright red, planktonic and called a "pentacula". By the end of May the larvae have evolved into juveniles and settled to the bottom.
From here on we know very little about the age and growth of the sea cucumber. After settlement the juveniles appear to hide among the rocks until they are 2"-3" long. Here they are relatively safe from predators and commercial drags. Practically nothing is known about the rate at which they grow or how long they live, except that their life span does appear to exceed seven years. The age at sexual maturity may be 4 to 5 years but that is not more than an educated guess.