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Red Sea Cucumber
Did You Know?
To get food, sea cucumbers ingest the substrate where they are located.
The red sea cucumber is part of the Phylum Echinodermata and the Class Holothuroideaia. It can grow to a length of 50 cm and a width of 5 cm, and when drained of fluids can weigh up to 500 grams. It has a soft, cylindrical body, with red-brown to yellowish leathery skin. It has an endoskeleton just below the skin. The mouth and anus are on opposite ends of the body. The mouth is surrounded by twenty retractable tentacles that are used to bring food in. Five rows of tube feet extend from the mouth to the anus. Tube feet are densely arranged on the ventral side and only three pairs of rows are distinct. Mobility is limited, though individuals can move up to 4 m per day while feeding. They use their tube feet located on the underside of their body. When threatened, it can expel all its stomach contents through its anus until its next feed. It has the ability to regenerate all parts of its body. It can also expel sticky filaments to ensnare or confuse predators.
Growth and Reproduction
Maturity is estimated to occur between 4 and 8 years of age and the maximum age is estimated as 12 years in British Columbia. Males and females are separate, breeding occurs in the summer, and development is indirect. The sperm have spherical heads and an unusually low DNA content. The fertilized eggs develop into auricularia larvae which metamorphose into doliolaria larva which settle. The pelagic phase lasts from 7 to 13 weeks in the laboratory.
This species is an epifaunal deposit feeder, feeding on organic detritus and small organisms and acting as a “bioturbator” that reworks and redistributes sediment in the process of feeding.
The hindgut bears a pair of highly branched diverticula, which project into the coelomic cavity of the body and serve as water lungs. Oxygenated water is pumped into these respiratory trees in several successive inhalations and then expelled in one powerful exhalation.
It is common for red sea cucumbers to undertake seasonal migrations to different depths. Mobility is limited so long distance migrations are not common.
Range and Habitat
It is a common species distributed from Mexico to Southeast Alaska and has been observed at least as far west and north as the Alaska Peninsula, Aleutian Islands, and Bering Sea. The abundance of sea cucumbers in Southeast Alaska is greatest in the southern and western portions in protected bays and inlets.
These sea cucumbers exist in a range of habitat types ranging from shell debris and gravel, mud and silt, and even exist on rock and boulders. A study conducted in Southeast Alaska showed that the most common habitat for sea cucumbers was shell debris and gravel. It occupies a broad range of subtidal habitats from nearshore shallows to over 100 fathoms. P. californicus appears to favor locations with moderate current, avoiding mud bottoms and areas subject to inundation by freshwater or glacial runoff.
Up to 50 cm long, up to 5 cm wide, up to 500 grams drained weight
West coast of North America, Mexico to Bering Sea
Plankton and organic matter
Sea otters, fish, crabs, sea stars
Males and females separate, fertilization is external
In Alaska, managed by the Alaska Department of Fish and Game
Did You Know?
- Sea cucumbers have feet that are used for locomotion.
- To get food, sea cucumbers ingest the substrate where they are located.
- Sea cucumbers can regenerate all parts of its body.
- The scale worm Arctonoe pulchra may occur as a commensal on the red sea cucumber.
Commercial and subsistence fishers harvest sea cucumbers in Alaska. The major products from this fishery are the longitudinal and transverse muscle bundles or meat, and the skins. Skin processing involves cooking or boiling the skins to a specific texture and drying the product. The dried skins are a preferred item in upscale oriental cuisine. Sea cucumbers harvested in Southeast Alaska have been processed in Craig, Juneau, Ketchikan, Petersburg, Sitka, British Columbia and the state of Washington.
There is a commercial fishery for P. californicus managed by the Alaska Department of Fish and Game by the Southeast Alaska Sea Cucumber Commercial Fisheries Management Plan (5 AAC 38.140). This plan seeks to protect subsistence opportunities and provides for sustained commercial fishing harvests. To protect subsistence opportunities, the cucumber management plan established 16 areas closed to commercial fishing (5 AAC 38.140 (k)). There are also provisions to prevent the use of diving gear in the subsistence (5 AAC 02.020 (1)) and personal use (5 AAC 77.010 (l)(3)) fisheries in those areas. Annual commercial fishery guideline harvest levels are 6.4% of the lower bound confidence interval of the total sea cucumber biomass taken on a three-year rotational basis (i.e. 19.2% once every three years). Rotational fisheries have the advantage of lowering overall departmental assessment survey and management costs.
See Southeast Commercial Dive Fisheries for red sea cucumber research.