Tubular Sea Cucumber, Holothuria tubulosa
Image Caption: Holothuria tubulosa. Credit: Rpillon/Wikipedia (CC BY-SA 3.0)
The tubular sea cucumber (Holothuria tubulosa), commonly known as the cotton-spinner, is the type species of its genus, Holothuria. It can be found in eastern areas of the Atlantic Ocean, with a range that extends as far as the Bay of Biscay to the north, in the Mediterranean Sea. It prefers a habitat within temperate areas and is found at depths of up to 330 feet below sea level, along the sandy floor or in muddy areas.
The tubular sea cucumber can reach an average body length between 7.9 and 18 inches, with an average diameter of about 2.4 inches. Its tough skin is similar to leather and is typically brown in color. It skin holds many darker brown papillae, which resemble thorns. Because this species releases a type of mucus from its body, it may appear to be gray in color. The bottom of this sea cucumber, like others, holds many suction-cup like tube feet, which allow it to move along the sea floor and attach itself to rocks.
Although this species has both male and female members, it is impossible to discern between them if viewed from the outside. In 2003, a large spawning event was witnessed in the Mediterranean Sea at the time of a full moon. Large numbers of this species gathered and lifted their back ends up in what is known as a spawning position. After raising themselves up, the sea cucumbers released gametes from genital openings, which can be found below the mouth. Individuals thought to be males first released a whitish material into the water, after which females emitted sticky fluids, which was thought to be a response to the release of male fluids. Eggs hatch about 24 hours after fertilization, and the larvae that are released float alongside zooplankton, consuming what algae they can until they are large enough to fall to the sea floor. Once they reach the floor, they undergo metamorphosis and grow into small sea cucumbers. The diet of the tubular sea cucumber consists of algae, detritus, and plankton.
The tubular sea cucumber, along with other species, is often harvested to be used as food in countries like Korea, Hong Kong, Taiwan, Singapore, and Norway. Between 2,000 and 3,000 individuals can be harvested in one day, and in some areas, divers must wait for a specific amount of time before harvesting again, in order to allow population numbers to grow again. Sea cucumbers can be sundried, frozen, or oven dried before shipped to other areas.