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The value of sea cucumbers
Sea cucumbers (class Holothurioidea) are echinoderms, an invertebrate animal characterized by their hard internal skeleton and the regular presence of a spine. To date, scientists have identified 1,400 species of sea cucumber, which are found in most of the world’s oceans, in shallow and deep waters and along and under the sea floor. Other familiar echinoderms include starfish, sea urchins and sand dollars.
While the species does appear in a wide range of colors, most sea cucumbers are brown, black or olive green. Their skin is leathery, with spiny plates concealed beneath the skin. They range from 1 inch long to more than 6-and-½-feet long. True to their namesake, sea cucumbers have elongated cylindrical bodies similar to the popular gourd.
Sea cucumbers are equipped with between eight and 30 tube feet around their oral opening, which they use to collect food from their environment and draw it into their bodies. Sea cucumbers are opportunistic feeders, subsisting on algae, zooplankton, small aquatic animal falls and waste materials. Of all that a sea cucumber ingests, waste materials are ecologically the most important. Similar to a terrestrial earthworm, sea cucumbers render waste material into smaller pieces, allowing bacteria to more readily decompose it.
Fish, crustaceans and marine mammals all predate on sea cucumbers. Some species have evolved deterrent behavior to thwart attacks, while other sea cucumbers have developed physiological traits making them unappealing. Some sea cucumbers contain exposed, hook-like skeletal structures, making them difficult to eat. Other species are able to expel a sticky, threaded discharge when they are threatened, entangling their predators. The quirkiest defense of some species is the ability to expel half of their internal organs from their body. While the marine animal who ingests these organs is dosed with a deadly toxin, the retreating sea cucumber will go on to regenerate its missing organs, taking approximately six weeks to complete the process.
Human beings are a sea cucumber’s most dangerous predators. A search on eBay found that dried sea cucumber is going for over $175 per pound. Some cultures consider this animal to be a delicacy, and it’s used during celebratory feasts and to honor special occasions. Some cultures also hold the belief that sea cucumbers will prevent the development of disease and increase one’s longevity.
With such a lucrative price tag, there is danger of over-exploitation. While sea cucumbers are currently stable on the conservation scale, the speed at which they are being commercially harvested is cause for concern. Sea cucumbers reproduce via external fertilization, and for reproduction to be successful there must be several healthy male and female specimens in a community. Over-exploitation threatens this healthy population.
The best way to aid in sea cucumber conservation is to avoid products containing the animal, and to speak up against its use if it is offered to you. When traveling abroad, avoid product names such as trepan and beche-de-mer, both names given to dried sea cucumber. And, as always, when encountering a sea cucumber in the wild, observe and photograph it — but don’t disturb it. These little guys are working hard to keep our oceans clean and they need their space.