Japanese Spiky Sea Cucumber

The Japanese sea cucumber has a cylindrical leathery body with blunt, thorny protuberances. At the anterior or front end there is a mouth surrounded by a ring of short feeding tentacles and at the posterior end is the anus. There are three different colour morphs, red, green and black.

The Japanese sea cucumber is found along the coast of Russia, China, Japan and Korea. The range extends from Alaska and Sakhalin Island to the Amami Islands, Japan. The red morphs are found on gravel beds offshore at depths of 40 metres (130 ft) or deeper while the other two colours are found intermingled on muddy and sandy bottoms at shallower depths. Although the red morph may breed red offspring due to its reproductive isolation in a different microhabitat, DNA studies have shown that there is a limited degree of genetic difference between it and the other two colour morphs while there is no significant difference between the black and green forms. In lagoons in southern Sakhalin, Russia, Japanese spiky sea cucumber are found on solid substrates among growth of the red alga Ahnfeltia tobuchiensis and in oyster beds (Crassostrea gigas).

The Japanese sea cucumber is used as food. The largest fishery is in Japan where between 2000 and 2005, an average of 8,101 tonnes of this species were harvested annually. The red form is known there as "aka namako" and sells at a different price from "ao namako", the green morph and "kuro namako", the black one. In Russia and North Korea, overfishing has reduced populations considerably. Fishing methods include diving and hand collection at depths of up to 20 metres (66 ft) and the use of trawls at greater depths. In the 1920s, a "sea cucumber fork" was developed in China. It is operated from several small vessels working together and allows harvest from depths of up to 60 metres (200 ft).