Crown-of-thorns

• ecologíaIt feeds on coral polyps and, without natural predators, its numbers can explode and badly damage entire reefs.
• anatomíaIt can carry dozens of arms, far more than the five most starfish have, and its spines hold a toxin that irritates human skin.
• A single adult can consume several square metres of living coral a year, and in population outbreaks there are tens of thousands on one reef.
• Its outbreaks are one of the main causes of coral loss on Australia's Great Barrier Reef, alongside bleaching and cyclones, and they are linked to the excess nutrients washing off the land.
• A female releases tens of millions of eggs a season, and one of its few known predators, the giant triton, has been decimated by collecting for its shell.
• It eats live coral. It everts its stomach over the colony and digests it externally, leaving the skeleton white. A single individual can consume several square metres of coral a year.
• Its outbreaks are responsible for 42% of the loss of coral cover on the Great Barrier Reef between 1985 and 2012, almost as much as cyclones and bleaching combined.
• The cause of those outbreaks is still debated. The main hypotheses are excess nutrients from agricultural run-off, which improves larval survival, and the fishing out of its predators; the models suggest both act together.
• A female can lay up to 60 million eggs in a season, and the larva spends about two weeks in the plankton.
• It is covered in venomous spines up to 5 cm long that cause intense pain, swelling and nausea.
• It is controlled by divers injecting individuals with bile salts or vinegar, one by one.

Habitat and environment

Indo-Pacific coral reefs, from 0 to 30 m

Litter / clutch size

Up to 60 million eggs per female per season

Sources consulted: Wikipedia (es): Acanthaster planci