Crown-of-thorns starfish (COTS) sound like something out of a science-fiction movie. Their brightly coloured bodies have up to 21 arms, all covered in barbed spines, hence the name crown-of-thorns.\u00a0<\/p>\n
Growing up to 80cm in diameter, these starfish can be bigger than a dustbin lid.<\/p>\n
How deadly are crown-of-thorns starfish?<\/p>\n
You don\u2019t want to get too close as COTS are the world\u2019s most venomous\u00a0starfish<\/a>. In case their tangle of sharp spines aren\u2019t enough to put off a would-be attacker, these sea stars reportedly exude a toxic slime.\u00a0<\/p>\n \u201cTheir spines are covered in plancitoxins which can cause liver damage. When threatened they also release saponins \u2013 compounds which destroy red blood cells,\u201d writes the Australian Institute of Marine Science (AIMS<\/a>) on its website. \u201cTogether, these toxins can cause great pain to any animal (or human!) unfortunate enough to come into contact with it.\u201d<\/p>\n Their venom can cause aches and pains, nausea, vomiting and\u00a0sometimes paralysis.<\/a><\/p>\n When one woman fell onto a crown-of-thorns starfish, she ended up with \u201capproximately 10 stab wounds of the left palm with pus, subcutaneous bleeding and many abrasions around them,\u201d according to the\u00a0study<\/a>\u00a0that documented the incident.\u00a0<\/p>\n There is only one recorded human fatality from these large sea stars: the venom caused\u00a0anaphylactic shock<\/a>\u00a0in the victim who died 13 hours after being stung.<\/p>\n Why are crown-of-thorns starfish a problem?<\/p>\n But crown-of-thorns starfish are worrying for another important reason: they are devastating\u00a0coral reefs<\/a>. Conservation experts are particularly worried about outbreaks in the Great Barrier Reef<\/a><\/p>\n As juveniles, these animals eat algae<\/a>. But adults have a voracious appetite for something else. \u201cAdult crown-of-thorns starfish have an enormous appetite for eating hard coral,\u201d explains the Australian Institute of Marine Science (AIMS<\/a>) on its website. \u201cAn adult crown-of-thorns starfish can consume up to 10 m2\u00a0of coral a year.\u201d<\/p>\n When COTS numbers get out of control, they can wipe out a reef in just a few weeks.\u00a0<\/p>\n The way they eat the corals is pretty grim. \u201cLike other starfish, they feed by pushing their stomach out through their mouth, covering their coral prey with digestive enzymes and converting coral tissue into a coral soup,\u201d says AIMS. \u201cWhen finished feeding they simply retract their stomach back into their body.\u201d<\/p>\n Killing these starfish is difficult. If people try to manage outbreaks by chopping them in two, it can make the situation worse. These predators \u2013 somewhat horrifyingly \u2013 can regenerate from the stumps and grow back into two\u00a0starfish<\/a>.<\/p>\n Instead, injecting them with vinegar or bile salts is much more effective.\u00a0<\/p>\n Not all marine animals are put off by the COTS\u2019 impressive self-defence measures. Their most famous predators are\u00a0giant triton snails<\/a> [MH1]<\/a>\u00a0\u00a0which follow the sea star\u2019s scent to locate their victim then pin it down with their strong foot and paralyse it with their\u00a0saliva<\/a>. Once it\u2019s subdued, they can gobble down their meal.\u00a0<\/p>\n \u201cResearchers estimated that, without these [predatory] starfish devouring coral, there would have been a net increase in average coral cover,\u201d says\u00a0the\u00a0Great Barrier Reef Foundation<\/a>\u00a0on its website.\u00a0<\/p>\n At least 18 reef fish also eat COTS, according to a study in\u00a0Scientific Reports<\/a>\u00a0that tested the poop and gut contents of different species to find which ones were eating the starfish.\u00a0<\/p>\n Scientists are even finding ways to use these predators as a way of protecting reefs because COTS flee when giant tritons are around. \u201cThere is nothing more alarming to a COTS then the scent of a giant triton,\u201d writes\u00a0AIMS<\/a>. \u201cIndeed, the very presence of a giant triton in the vicinity of a COTS is enough to cause the starfish to rapidly move away.\u201d\u00a0<\/p>\n","protected":false},"excerpt":{"rendered":"Crown-of-thorns starfish (COTS) sound like something out of a science-fiction movie. 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