Crown of Thorns
⚠ VENOMOUS — CORAL PREDATOR — HANDLE WITH EXTREME CARE
The Crown of Thorns is a serious coral-eating pest covered in sharp, venomous spines. A puncture is intensely painful and can cause swelling, nausea, and infection. It will rapidly destroy corals in a reef tank. This page is provided for identification and awareness — it is not recommended for the home reef aquarium.
Acanthaster planci
| Identification | Large, multi-armed (up to 21 arms) starfish densely covered in long, sharp, venomous spines. Colors range from gray-green to red and purple. |
| Origin | Indo-Pacific reefs |
| Maximum Length | 12–18+ inches across |
| Minimum Tank Size | Not recommended for home aquaria |
| Reef Compatibility | NO — one of the most destructive coral predators known |
Behavior
The Crown of Thorns is an infamous coral-eating starfish responsible for devastating wild reefs during population outbreaks. It climbs onto corals, everts its stomach over the colony, and digests the living tissue, leaving bare white skeleton behind. In an aquarium it will rapidly consume corals. It is covered in long, sharp spines coated in venom (saponins) that make handling hazardous. This page is provided so hobbyists can identify it and understand why it is not a reef-tank animal.
Diet & Feeding
Corallivore — eats live coral tissue, strongly preferring stony (SPS) corals. It digests coral externally by everting its stomach over the polyps. There is no way to keep it without sacrificing corals, which is one reason it is unsuitable for reef systems.
Cautions
VENOMOUS — the spines cause intensely painful puncture wounds with swelling, nausea, and possible infection; some people react severely. Never handle with bare hands; use thick gloves and tongs, and seek medical attention for stings. Removing broken spines is difficult. Destroys corals rapidly. Not recommended for the home reef aquarium — this is an identification/awareness page.