Identification:
The body is nearly cylindrical and elongated, bulging in the middle and tapering at both ends. Adults range in length from 150 to 250 mm, with a diameter of 30 to 50 cm; the body wall is thick. The dorsal surface is dark brown when alive and has numerous small fleshy projections that resemble durian spines; the ventral surface is lighter in color and has many small tube feet arranged in longitudinal bands. The mouth, located anteriorly, has 20 large and short tentacles, with the tentacle tips flared out like a parasol. The anus, located posteriorly, possesses 5 calcium spines.
Biology and Ecology:
This species is dioecious (has separate sexes). Fertilization occurs in seawater, with reproduction taking place during the warm season (March-June). Absolute fecundity ranges from 4 to 25 x 106 eggs (Conand, 1986). Eggs develop through larval stages before becoming juveniles that settle on the seabed. The average monthly growth rate is 10-20 cm in length and 20-23 g in weight. This species lives in the intertidal zone, commonly found at depths of 2-4 meters, on sandy substrate covered by dead coral.
Distribution:
- In Vietnam: Along the coast of the Central region and on islands: Con Dao, Phu Quoc – Tho Chu.
- Worldwide: Indo-West Pacific region.
Value:
Valuable for scientific research on benthic organisms living in the intertidal zone.
Conservation Status:
Prior to 1990, this species was commonly found along the coast of the Central region and on islands. Since 1990, due to increased harvesting for food in Vietnam and for export, the population has significantly declined, potentially decreasing by 20% annually. The species is now depleted and difficult to find. The distribution area of this species was estimated to be 6000 km2 before 1990. Currently, due to intensive harvesting, combined with habitat loss and pollution from coastal construction, the area has shrunk to no more than 3000 km2. Population size also fluctuates considerably from year to year, depending on harvesting practices.
IUCN Assessment:
VU A2d B2e+3d (Vulnerable)
Conservation Measures:
Listed in the Vietnam Red Data Book (1992 & 2000). Recommendations: Reduce harvesting intensity and restrict harvesting to mature individuals after the breeding season. Prohibit harvesting of dead coral and limit the construction of coastal structures that lead to habitat loss and environmental pollution. Research is needed on artificial propagation to replenish wild populations.