Posted by: glennandert | 7-September-2008

Crown of Thorns

This post is about the Crown of Thorns starfish.  It is quite an impressive looking creature covered with thorns for protection, hence the name. In addition to being sharp, the spines are poisonous to humans and predators. In a way it is quite beautiful.

It is a voracious predator of coral reefs in many parts of the world. It climbs onto the coral, covering the polyps with its stomach, releasing digestive enzymes and absorbing the coral’s tissue. They can wipe out large areas of coral. The Great Barrier Reef is threatened by outbreaks of this starfish.

The following photo shows a crown of thorns on the underside of what remains of a coral. You can see the purplish arms of the crown of thorns reaching up and around the white coral.

The flowering creature standing on the rock to the left is a crinoid, which we have discussed in an earlier posting.

The Crown of Thorns has very few predators. However, I’ve read that the large humphead wrasse will feed on small ones. A large marine snail known as the Pacific Triton, or Triton’s trumpet, is also a predator. But, it has a beautiful shell and is one of the largest and most prized of all marine snails. Decimation of this snail by shell collectors has led to overpopulation of the crown of thorns, and the destruction of vast reef area.

There is a fine introductory article on the Crown of Thorns on Wikipedia.

The following photo shows a coral with one crown of thorns animal on top and another on the bottom! Yum – coral sandwich!

The following is a close up of the same pair of animals.

These photos were taken on a night dive on the outer reef at Mana Island, Fiji. See this post for further details.



  1. Your photography is amazing! Sea creatures have a unique beauty that is all their own!

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