Sea cucumbers are echinoderms in the class Holothuroidea.
This photo is of a Pacific white-spotted sea cucumber, which is also known as the Hawaiian sea cucumber. I saw this wild looking animal while snorkeling in only a few feet of water with my wife at Anini Beach on the north shore of Kaua'i. At first glance you might mistake a sea cucumber for something other than a fish, but then you realize that it's alive and moving! Let's learn about the wild wold and life of sea cucumbers!
What is a Sea Cucumber
Sea cucumbers are echinoderms in the class Holothuroidea. Other echinoderms include starfish and sea urchins. They are marine invertebrates that live on or near the sea floor. There are about 1,500 species of sea cucumber. They are found in all the world's oceans. Sea cucumbers have a tubular body with a soft skin. They vary in color from pink, green, yellow, or brown. The Pacific white-spotted sea cucumber (Hawaiian sea cucumber) has a brown body with white spots.
Anatomy of sea cucumbers
Sea cucumbers are invertebrates which means they have no backbone. They are typically four to twelve inches long, but the longest sea cucumber ever was ten feet. They are spherical and worm like with a mouth surrounded by a ring of tentacles. Sea cucumbers have four rows of tube feet which they use to move around. They have another set of modified tube feet, which are around their mouth, that they use to feed. They do not have a true brain, but they do have neural tissue around their mouths. Sea cucumbers have an endoskeleton made of calcium carbonate. In most, this has been reduced to microscopic ossicles; however, for a few genera, it protects them from predators.
Diet of Sea Cucumbers
They live on the sea floor and get their food from the sand and sea water. Sea cucumbers are scavengers, meaning they primarily eat debris on the sea floor. They will eat plankton, algae, and dead animals. Some sea cucumbers can catch food with their tentacles. The aforementioned modified tube feet, or tentacles, around their mouths, are typically adapted to their diets. Those living on fine sand or mud will have smaller tentacles, while filter-feeding species have arborescent, or tree-like, tentacles to maximize the surface area for filtering.
They do not have a true brain, but they do have neural tissue around their mouths.
There are 14 species of sea cucumbers in Hawai'i.
Sea Cucumbers of Hawai'i
There are 14 species of sea cucumbers in Hawai'i. The Hawaiian word for sea cucumber is loli. Sea cucumbers have been eaten and used for medicine in Hawaiian culture. Pictured here is the Pacific white-spotted sea cucumber. The scientific name for this sea cucumber is Actinopyga varians. Other species found in Hawai'i include the black sea cucumber, ashy cucumber, banded sea cucumber, and the white-speckled sea cucumber.
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