Identification:
The body is shield-shaped and elongated, with a curved dorsal surface and a slightly flattened ventral surface. Adults are quite large, ranging from 300-400 mm in length and 50-70 mm in diameter. Along the back and sides, there are rows of raised, fleshy bumps that resemble nipples. When alive, the dorsal surface is usually black or grayish-brown, while the ventral surface is lighter in color. The body wall is thick and rigid. The mouth has 20 yellow tentacles that spread out in a fan shape. The anus has five calcium spines, each surrounded by a cluster of soft, fleshy spines.
Biology and Ecology:
This species is dioecious (separate sexes), reproducing in warm water seasons and undergoing sexual rest during cold water seasons. Fertilization occurs in seawater. Absolute fecundity (potential egg production) ranges from 13 million to 78 million eggs. The primary food source of this species consists of benthic (bottom-dwelling) material encountered along its path, including both animal and plant matter. It inhabits the intertidal zone at depths of 4-15 meters, commonly found on sandy-mud bottoms or dead coral reefs.
Distribution:
- Within Vietnam: Coastal waters of Phu Yen, Khanh Hoa, Binh Thuan provinces and the islands of Truong Sa and Con Dao.
- Worldwide: East Africa, East India, the Western and Southern Pacific Ocean.
Value:
Valuable for scientific research on marine organisms living on sandy-mud bottoms or dead coral reefs.
Conservation Status:
Prior to 1990, it was occasionally found in coastal waters of central Vietnam and some islands. Since 1990, the population has significantly decreased due to increased harvesting for domestic consumption and export. It is now depleted and difficult to find. The distribution area of this species was estimated to be 7,000 km² before 1990. Currently, due to intensive exploitation combined with habitat loss and pollution from coastal construction, the distribution area has been reduced to no more than 3,000 km² and the population numbers are very low.
IUCN Red List Status:
VU A2d B2e+3d (Vulnerable)
Conservation Measures:
This species is listed in the Vietnam Red Book (1992 & 2000). Recommendations include reducing the intensity of exploitation and harvesting only mature individuals (length > 300 mm) after the breeding season. Restricting the construction of coastal structures to prevent habitat loss and environmental pollution is also recommended. Artificial reproduction research and supplementation of the wild population are needed.