Identification:
- Morphology: The body is nearly cylindrical and elongated. Adults range in length from 200 to 350 mm and have a diameter of 35 to 50 mm. The dorsal surface is typically dark brown or grayish-white, speckled with areas of varying colors (darker or lighter) and sparsely covered with irregularly arranged papillae. The ventral surface is lighter in color and bears numerous small tube feet that are not arranged in rows. The mouth is slightly angled towards the ventral side and has 25 large tentacles. The anus is angled towards the dorsal side and has 5 large calcareous spines, with a white ring surrounding the anus.
Biology and Ecology:
- Reproduction: This species is dioecious (separate sexes) and reproduces during the warm water season. Its biology has not been thoroughly studied. It inhabits the sublittoral zone, typically found at depths of 2-5 meters, on sandy substrates covered by dead coral.
Distribution:
- Vietnam: Coastal areas of Phú Yên, Khánh Hòa, Ninh Thuận, Bình Thuận provinces, and the islands of Trường Sa, Côn Đảo, Phú Quốc – Thổ Chu.
- Global: Indo-West Pacific region.
Value:
- Of scientific value for the study of benthic marine animals that inhabit sandy environments.
Conservation Status:
- Historical: Prior to 1990, this species was relatively common along the central coast of Vietnam and its islands.
- Decline: Since 1990, due to increased exploitation for food (domestic and export markets), the population has significantly declined, with a decrease of over 20% per year. It is now depleted and difficult to find. The distribution area of this species before 1990 was estimated to be 7500 km². Currently, due to intensive exploitation and habitat loss and pollution from coastal construction, the area has shrunk to no more than 4000 km²; its population numbers are very low.
- IUCN Classification: VU A1d B2b,e+3d
Conservation Measures:
- Listed: Included in the Vietnam Red Book (1992 & 2000).
- Recommendations:
- Reduce the intensity of exploitation and harvest only mature individuals after the spawning season.
- Prohibit the exploitation of dead coral and limit the construction of coastal structures that destroy habitat and pollute the environment.
- Research artificial reproduction to replenish wild populations.