Crown-of-thorns Starfish
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- Name / Latin
- Crown-of-thorns Starfish — Acanthaster planci
- Brief description
- A large coral-eating sea star with numerous poisonous spines and 12–19 rays. Feeds on living corals and during population outbreaks can cause serious damage to reefs.
- Size:
- usually 25–35 cm, maximum up to 60 cm in diameter
- Depth:
- 0.5–65 m
- Habitat:
- Red Sea, Indian Ocean, Western Pacific Ocean
- Family:
- Acanthasteridae
- Type:
- Echinoderms
- Activity:
- predominantly nocturnal
- Conservation status:
- Not Evaluated (NE) — species not evaluated by the International Union for Conservation of Nature (IUCN)
The crown-of-thorns starfish (Acanthaster planci) is a large sea star reaching up to 60 cm in diameter. It has many long, pointed arms, usually from 12 to 19, covered with poisonous spines. The spines cover both the upper and lower surfaces of the arms and body. The color varies from red and purple to green and brown, which helps this sea star camouflage among corals.
The crown-of-thorns starfish inhabits tropical and subtropical waters of the Indo-Pacific, from the Red Sea to Central America. It prefers coral reefs at depths from 1 to 30 meters, but is sometimes found at greater depths.
The crown-of-thorns starfish is a coral-eating sea star. The main source of food for it is hard corals, which it digests externally: by everting its stomach outward, it secretes enzymes that break down coral tissue. This can lead to significant destruction of coral reefs, especially during population outbreaks.
Reproduction in the crown-of-thorns starfish occurs through spawning. Females can produce up to 60 million eggs in one spawning. Eggs and sperm are released into the water, where external fertilization occurs. The larvae develop in plankton and after several weeks settle to the bottom, transforming into a young sea star.
The crown-of-thorns starfish poses a danger to divers due to its poisonous spines. Touching the spines can cause severe pain, swelling, nausea, and even paralysis. Wounds from the spines can heal very slowly and be prone to infection.
