Long-spined Crown-of-thorns

Overview

The Long-spined Crown-of-Thorns (Acanthaster planci) is a large, distinctive sea star known for its significant ecological impact on coral reefs. It is easily recognized by its numerous arms and a body covered in long, sharp, venomous spines that serve as a potent defense mechanism.

Appearance

This species features a large, flexible central disk surrounded by 9 to 23 short, thick arms. Its coloration is highly variable, ranging from shades of gray-green and olive to reddish-brown or bluish-purple. The aboral (upper) surface is densely armored with stiff, thorn-like spines that can reach approximately 5 cm in length. These spines contain toxins that can cause severe pain, nausea, and vomiting in humans if touched.

Distribution & habitat

Found throughout the tropical and subtropical Indo-Pacific, this starfish inhabits coral reefs and hard coral communities. Its range extends from the Red Sea and East African coast across the Indian Ocean to the Pacific, reaching as far as the west coast of Central America.

Feeding

As a specialized corallivore, the Crown-of-Thorns feeds primarily on stony coral polyps. It consumes coral by extruding its stomach over the substrate, digesting the living tissue externally and leaving behind only the white, calcium carbonate skeleton. While primarily nocturnal, individuals may occasionally be observed active during the day.

Reproduction

This species reproduces through external fertilization. During synchronized spawning events, males and females release vast quantities of gametes into the water column. The resulting larvae are planktonic, drifting for several weeks before settling on the reef to undergo metamorphosis into juveniles.