The crown-of-thorns starfish

Another Crown-of-thorns starfish was spotted just the other day around Koh Tao, giving us all the interest to further inspect these beauties. Beneficial yet capable of great danger to both coral and divers.

The Crown-of-thorns starfish recieved its name from the venomous thorn-like spines that covers the entire body, creating a crown-like shape. These spines can pierce through wetsuits, a fact that has made divers gain the respect this starfish should be treated with. The starfish can produce a neurotoxin, released through the spines, causing a sharp long-lasting stinging pain, nausea and potential vomiting. The area around the wound will turn dark blue and begin to swell, possibly lasting for weeks. Even worse, if the spine breaks off and stays under the skin, it can lead to increased toxicity and infection.

But not only can these creatures cause damage to humans, they also have a big impact on the coral reef.

Because of its spines, the starfish are a very unattractive target for other reef predators. This eliminates most enemies and therefore provides power to the animal. This can lead to overpopulation. But what does it mean for the reef?

Overpopulation of crown-of-thorns can cause great reef destruction. Some biologists even believe that its one of the most influential species in the diverse biotic communities that make up tropical coral reefs. The Crown-of-thorns, sometimes just referred to as Crownthorn starfish, has a very important role in maintaining the biodiversity, preventing fast-growing coral from overpowering the more slower growing ones.

The changes our seas are going through such as environmental pollution and coral bleaching means an increased risk of overpopulation. Consequences of this may mean a supply of alternative food sources to the predators of the crown-of-thorns.

To prevent overpopulation humans have a variety of control measures. What we can do, is inject sodium bisulphate into the starfish. This does not harm the surrounding reef and ecosystems but it does prevent a “crown-of-thorns epedemic”.

This needs to be done with much care though; When under stress or if dismembered the animal has a bit of an “alien”-effect – it will start to proliferate.

In summary, when treated with respect and the requried knowledge, the crown-of-thorns starfish is another wonder of the sea that will continue to be admired by divers all over the world and preventing overpopulation we can keep our ecosystem in tact.

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