Crown-of-Thorns starfish
|
|
| Crown-of-Thorns starfish | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Missing image Crown_of_thorns_starfish.jpg A Crown of thorns starfish, Saipan, 1969 | ||||||||||||||
| Scientific classification | ||||||||||||||
| ||||||||||||||
| Binomial name | ||||||||||||||
| Acanthaster planci [[]], [[]] |
The Crown-of-Thorns starfish (Acanthaster planci) is a red-colored starfish with thorn-like spines sprouting all over its body for protection. These echinoderms grow to a diameter of up to 40 cm across and have 12-19 arms extending from their center.
If accidentally touched or stepped on by humans, the starfish's long spines are capable of pricking and stinging, inflicting great pain that can last up to hours. Other symptoms include nausea and vomiting. Frequently, the area around the puncture turns a dark blue (erythema) and begins to swell (oedema). The swelling may persist for a number of days.
Crown-of-thorns starfish are found on coral reefs in the tropics ranging from the Red Sea, throughout the Indian and Pacific Oceans, and all the way to the Pacific coast of Panama.
The starfish is a coral reef predator (a corallivore) and preys on the coral polyps by climbing onto them, extruding the stomach over them, and releasing digestive enzymes to then absorb the liquified tissue. They feed alone at night, maintaining a constant distance between themselves and other Crown-of-Thorns starfish. During times of food shortage, these creatures can live on their energy reserves for over six months.
Populations of the Crown-of-Thorns starfish have increased since the 1970s and this species is at least partly responsible for much loss of coral reefs, particularly on the Great Barrier Reef in Australia. They are voracious predators that can wipe out large areas of coral; an individual one can consume up to 13 square miles of it per year.
Outbreaks of huge numbers of these starfish are believed to be caused by agricultural runoff which causes algal blooms.
Few animals in the sea are willing to attack the spiny and toxic Crown-of-Thorns starfish, but surprisingly, some sea creatures actually prey on them. Predators of Ancanthaster planci include the Giant Triton Shell (Charonia tritonis), a species of shrimp, a species of worm and various reef fish which feed on eggs, larvae or small adults. It may be possible as well, that the decline of these predators (through overharvesting, pollution etc.) has been a factor that lead to the rise in the population of the starfish.
Ancanthaster planci, the Crown-of-Thorns starfish, due to its notorious damage to reefs, has been described as one of the most influential species in the diverse biotic communities that make up tropical coral reefs (Birkeland, 1985).ru:Терновый венец