Coral Reefs Under Attack by Spiny Sea Stars!!!

When you think of starfish, killer is not usually the first word to come to mind. Growing up we think of starfish as majestic, golden creatures with the traditional five arms, often cute, soft and squidgy. This view is shattered when you discover the Crown-Of-Thorns Starfish.

Crown-of-thorns starfish hiding under a rock in a coral reef, Beqa Lagoon, Fiji

These spiky monsters can have up to 21 arms and may reach 40cm across, their entire bodies covered in hard, venomous spines. But why is this starfish a well-renowned monster and possibly the most hated starfish on the planet? It’s a savage coral killer.

Within the recent years it’s become common knowledge that the earth’s majestic coral reefs are dying, being bleached to oblivion. While this is most likely due to human impact, the Crown-of-thorns starfish decides to lend a helping hand.

The starfish is a predator that feeds on living corals, crawling across them using its tube feet and turning out its stomach to digest the coral and absorb its nutrients. Once complete, it moves on leaving a white, bleached scar. In small densities, this is never usually an issue as the starfish can feed on other corals in the reef while the previous coral replenishes – controlling coral growth. But recently this has been an issue as their populations plague the tropical reefs they inhabit.

Bleaching patterns characteristic of Crown-of-thorns, when you see this the starfish are nearby!

Most commonly found on the Indo-Pacific reefs, outbreaks of the Crown-of-thorns are becoming more dramatic and deadly for the reef system. The Great Barrier Reef, usually near the top of everyone’s bucket list of places to visit, has nearly lost all of its colour, remaining a ghost town of dead coral and white scars. Not only is this bad for tourism but it’s extremely damaging to the ecosystem. The fish that live in coral reefs require healthy corals for survival, without this their populations will fall, leading to falling populations of bigger fish and so on until the entire ecosystem collapses.

But what does this have to do with us? Well, humans are most likely the cause of these outbreaks. Climate change has been near proven to warm the oceans which is beneficial to the growth of the sea star and its reproduction. In addition to this there has been a decline of the starfish’s predators which, due to its venomous spines, the creature has very few of. The main predator, Triton’s Trumpet, has experienced mass over collecting for its shell. As well as this habitat destruction has caused predator populations to decline – something that’s very common on reefs due to clumsy tourists.

While this may just sound like a story of doom and gloom, there Is something we can do to try and help. The usual climate change reducing impacts will benefit in the long run but this could occur too late. Many divers have taken it upon ourselves to reduce the population of Crown-of-thorns by carefully killing or removing them from the ocean. They cannot be cut up or pierced as this would cause more to spawn, so if professional methods are not available the best thing is to remove them from carefully from the corals using a rod and placing them in a bucket to take them out of the ocean.

These starfish are extremely good at hiding so there will always be more around than can’t be seen. Removing any that you see is going to have the quickest benefit to the corals, and over all, our planet. But whatever happens, be extremely careful and try not to get stung! Speaking from personal trauma – it will most likely be the most painful experience of your life!

5 years ago

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