Crown-of-thorns starfish

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A crown of thorns starfish
Unusual brightly coloured crown-of-thorns starfish, Thailand

The crown-of-thorns starfish (Acanthaster planci) is a type of sea star. Usually, they have orange-red to purplish skin, with yellow or pink spikes on their skin. The crown-of-thorns is also one of the largest starfish in the world, as it has a diameter of up to 3 feet. The crown-of-thorns lives in the warmer areas of the Pacific Ocean, Indian Ocean, and Red Sea.

It only feeds on coral polyps, and usually at night. The crown-of-thorns climbs over its prey, releases digestive enzymes to break down its food, and then absorbs the coral polyp, which has now turned into a liquid. What's left behind by the sea star is the leftover coral skeleton.

They are usually of subdued colours, pale brown to grey-green, but they may be garish with bright warning colours in some parts of their wide range.[1][2] These bright colours warn animals that may want to eat it that it is venomous.

Effect on coral reefs[change | change source]

The crown-of-thorns is well known for its destructive habits of eating coral, especially on the Great Barrier Reef, which is a World Heritage Site. Usually, when there are not too many of them, these sea stars help maintain the coral reef by preventing the faster-growing coral from taking over the coral reef. However, when there are too many crown-of-thorns, they can devastate the reef.

References[change | change source]

  1. Birkeland and Lucas (1990). Acanthaster planci: major management problem of coral reefs. Florida: CRC Press. pp. 97–98. ISBN 0-8493-6599-6 .
  2. Shedd, John G. (2006). "Crown of thorns sea star". Shedd Aquarium. http://sea.sheddaquarium.org/sea/fact_sheets.asp?id=69. Retrieved 2013-06-29.