Identification:
Colony morphology: Branching, bush-like or shrub-like formations with multiple dichotomous branchings, resembling bamboo clumps. Branch tips are slightly enlarged. The outer layer (cortex) is very thick, especially at the branch tips. The skeletal elements (spicules) within the cortex are star-shaped, approximately 0.2mm long, with small nodes; some are irregularly shaped with a diameter of 0.1mm. The main axis is thick at the base and on the main branches, becoming smaller on the lateral branches and slender at the branch tips. The axis is segmented, with black, horn-like segments that are typically small and short, interspersed with larger, longer white segments composed of calcium. Longitudinal grooves run along the axis, being very prominent on the white segments. Living specimens exhibit a pale brown color.
Biology and Ecology:
Distribution: Found on coral reefs near islands far from the mainland, in areas with very clear water, high and stable salinity (>33‰), and minimal wave action. Commonly found in lagoons within the Spratly Islands, at depths ranging from 1 to 20 meters. In areas with low wave action and weak currents, colonies grow larger (up to 1 meter in height). In areas with strong waves and currents, the colonies are smaller (20-30cm).
Distribution:
- Within Vietnam: Spratly Islands.
- Worldwide: Islands in the central Pacific and Indian Oceans.
Value:
Used for handicrafts.
Status:
In Vietnam, this species is currently only found in the Spratly Islands, with a limited distribution area. Prior to 1990, the population was relatively abundant and easily found. However, due to intensive harvesting for souvenirs and handicrafts, the population has significantly declined, especially in shallow waters.
Conservation Status:
VU A1a,d C2a (Vulnerable).
Conservation Measures:
Listed in the Vietnamese Red Book (1992-2000). Currently, a five-year moratorium on harvesting is needed to allow for population recovery. Further biological research is required to establish a basis for sustainable and responsible harvesting and development of this resource.