Holothuria parvula

Holothuria parvula, commonly known as the golden sea cucumber, belongs to the echinoderm class Holothuroidea. Its full scientific name is Holothuria (Platyperona) parvula, as it was first described by Emil Selenka in 1867 and later placed in the subgenus Platyperona. This species inhabits shallow waters of the Caribbean Sea and the Gulf of Mexico, and it stands out among sea cucumbers for its ability to reproduce by splitting in two.

Description

This sea cucumber has a roughly cylindrical body, with tube feet on its underside and conical, wart-like bumps on its upper surface. Its coloration is golden.

Distribution

Its range includes the tropical western Atlantic, the Caribbean Sea, and the Gulf of Mexico, specifically Bermuda, the West Indies, the Bahamas, the Lesser Antilles, Colombia, and Venezuela. It lives on sandy seabeds in shallow water.

Biology

Holothuria parvula feeds on detritus, algae, and plankton, moving across the seabed or over rocks using its tube feet. When threatened or stressed, it can expel sticky threads called cuvierian tubules from its anus. These threads contain a toxin known as holothurin, which entangles small fish or crabs, preventing their escape and leading to their death. The sea cucumber then moves away and eventually regenerates the tubules.

Asexual reproduction occurs through transverse fission. In Bermuda, this happens during summer when water temperatures reach at least 25 °C (77 °F). A split forms in the body wall, deepens, and extends across the body until it breaks apart. The two resulting pieces are roughly equal in size, and each can regenerate missing organs.

The gut is crucial for survival; both front and rear sections can resume feeding within two months, while the gonads take longer to regenerate. In a study of the Bermudan population, no juvenile specimens were found, leading researchers to believe that little or no recruitment from planktonic larvae occurs. Instead, fission appears to be an annual event and the primary means of reproduction.