Holothuria leucospilota

Holothuria leucospilota, known as the black sea cucumber or black tarzan, belongs to the family Holothuriidae. Its full scientific name is Holothuria (Mertensiothuria) leucospilota, and it serves as the type species for the subgenus Mertensiothuria. This marine invertebrate lives on the shallow seabed across the Indo-Pacific.

Description

When relaxed, this medium-sized sea cucumber reaches up to 40 centimeters in length, but it can stretch to about a meter when extended. Its body is roughly cylindrical and tapers toward the rear.

At the front, twenty branched oral tentacles surround the mouth, which sits on the underside. The animal is soft and pliable, covered in fleshy papillae. Its usual color is charcoal gray or reddish-black, with pale gray tube feet underneath; off the African coast, however, it appears bright or dark brown with white patches that grow larger toward the rear.

Distribution

The species inhabits shallow waters along East Africa and much of the Indo-Pacific. It is common on Australia’s northeast coast, where it lives on reefs and rocky shores, often partly hidden under boulders. A study near Singapore found it more abundant near boulders, corals, and seaweed clumps than on open seabed.

This sea cucumber tolerates changes in salinity and temperature relatively well, thriving in the lab when these conditions shifted. In contrast, the Japanese sea cucumber (Apostichopus japonicus) shrank, eviscerated, and died within three days under the same conditions. In Singapore, A. japonicus is eaten and has become increasingly rare due to overexploitation.

Biology

Holothuria leucospilota is a scavenger. While feeding, it usually anchors its rear end under a rock or in a crevice so it can contract back out of sight if disturbed. It uses its tentacles to shovel organic debris—along with a significant amount of sand—into its mouth; the sand passes through its gut.

When threatened, it can expel a mass of fine, sticky Cuvierian tubules from its anus to entangle predators, allowing escape. These tubules regenerate in fifteen to eighteen days. The worm pearlfish (Encheliophis vermicularis) parasitizes this species; each infected H. leucospilota hosts a male-female pair of the fish living inside its body.