Holothuria spinifera

Holothuria spinifera, also called the brown sandfish, is a sea cucumber belonging to the family Holothuriidae. Its full scientific name is Holothuria (Theelothuria) spinifera, placing it in the subgenus Theelothuria.

In India, it is known locally as cheena attai or raja attai. This species inhabits tropical waters of the western Indo-Pacific Ocean, at depths between 32 and 60 metres. It is harvested commercially for processing into beche-de-mer.

Description

The body of Holothuria spinifera is cylindrical, dark brown on top and pale brown underneath. Its skin is thickly covered with sharp, cone-shaped bumps. It can reach a length of 30 centimetres.

Biology

A scavenger, the brown sandfish uses its tentacles to sift through sediment on the seafloor. It typically stays buried during the day and emerges at night. Research on its reproduction and life cycle has been carried out to explore commercial breeding for aquaculture or sea ranching. In one Indian study, adults were collected by hand and placed in a tank, where spawning occurred spontaneously.

A male released sperm in a white strand, and a female responded by releasing a spurt of eggs, which were fertilized in the water column. The resulting larvae were pelagic and developed quickly, feeding on microalgae for the first ten days. Over the next four days, they entered a non-feeding, barrel-shaped doliolaria stage, moving around the tank.

They then settled on the bottom and transformed into pentactula larvae, with five short tentacles at the front and two tube feet at the rear. By day twenty, the tentacles and feet were more distinct, and the first thorny bumps appeared on the body. Larval mortality in the study was about 95%, partly due to predation by copepods that could not be removed from the tank. Other studies have looked at how to best trigger spawning and the ideal temperature, pH, and salinity for rearing larvae, as well as the best diet and methods to encourage settlement.

Ecology

In Vietnam, a small bivalve called Entovalva nhatrangensis lives as an endosymbiont inside the oesophagus of Holothuria spinifera. This mollusc is a filter feeder, getting nourishment from sediment the sea cucumber has swallowed.

Use as food

In India, both Holothuria spinifera and the sandfish (Holothuria scabra) are collected for food. The best method is to gather them by skin diving and handle them gently.