Warty sea cucumber

Natural history

Oral tentacles, which surround the mouth, are part of the cucumber’s water vascular system (hydraulic pressure at its finest!). These tentacles have an adhesive-like mucus that is used to pick up detritus. Tentacles covered in detritus are then placed in the mouth and “licked clean.”

An intestinal tract connects the mouth and anus on opposite ends of the warty sea cucumber's body. A respiratory tree—a collection of thin-walled tubes—stems from the intestinal tract and serves as water lungs. The sea cucumber draws water through its anus into the tree, where respiration takes place. When the oxygen is depleted from the water, it is then forcefully expelled back through the cloaca and anus.

Conservation

In California, commercial fisheries seek two species of sea cucumbers—warty and California—that are shipped to Asian markets both here and overseas. Commercial fisheries need a permit to fish for sea cucumbers, but there are no restrictions on the number of animals caught. Worldwide, many sea cucumber fisheries have collapsed as a result of overfishing.

The demand for sea cucumbers in Asian markets, where people value them as a food and as a medicine, is large. To fill the void, people began fishing for sea cucumbers in the waters near the Galapagos Islands in 1988. In 2001, the Inter-institutional Management Authority agreed on regulations that allow resident fishermen to catch four million sea cucumbers each year in established fishing zones near islands.

Cool facts

• Each fall, the warty sea cucumber finds a secure place to hide and expel its viscera—including the gonads, circulating system, and respiratory tree—a process called evisceration. This annual evisceration allows the sea cucumber to rid itself of sediment that builds up as they sift and eat detritus. Within two to four weeks, the viscera regenerate.
• Warty sea cucumbers also use evisceration to ward off predators—distracting them as they scoot away. A warty sea cucumber may also eviscerate other times it is uneasy: if it is roughly handled by humans or even if it finds the water too warm.
• Warty sea cucumbers and their related species are sometimes called the "earthworms of the sea," as they cultivate the seafloor in much the same manner as earthworms cultivate the soil. They oxygenate the top layers and filter sediments, which limits the build up of decomposing material and makes the seafloor more habitable for benthic burrowers.
• In areas where overfishing has reduced the population of sea cucumbers, the seafloor hardens, thus destroying a habitat for other bottom-dwelling creatures.