Today I will be talking about the infamous Crown of Thorns Sea star (Acanthaster planci). First and foremost, these are not an invasive species here but are indigenous to the Indo-Pacific. Coral is apart of their main diet and in a balanced ecosystem, with their populations in normal numbers, they would eat the faster growing corals allowing the slower ones to “catch up” and increase reef diversity. However, due to the recent outburst, which is believed to be due to excess nutrients from land runoff and removal of their predators, they are decimating the corals! The first COTS outbreak was recorded in 1962 with the most recent in 2010 that is still ongoing. If you didn’t know already... these are some pretty freaky animals! They can have any where from 7-23 arms and grow to 35, even 80cm!! They’re also covered in spines that ARE poisonous to both humans and marine organisms, except for the few that can eat them like the Titan Triggerfish, Giant Triton Snail, Starry Pufferfish, and the Humphead Maori Wrasse. The other joy is that they have a high fecundity, with a female able to produce as many as 55 million eggs in one breeding season. Not all hope is lost though, because there is active work being done to remove them from the reef as well as research trying to better understand them. This has made COTS one of the most studied animals in the world due to the threats they are posing to the already struggling reefs. Believe it or not, COTS and cyclones are responsible for the greatest number of coral deaths!! Although many divers are trained in properly removing COTS, the standard rule is if they have been pricked more than 2x, they can no longer help. The best removal approach was an injection method actually developed here at JCU (James Cook University)! This injection causes an allergic reaction within the COTS, causing them to die and break apart within 24 hours!!! Here’s to hoping the efforts continue to be successful and the corals can have one less threat to deal with!
Originally posted 1 September 2019
(not my pictures)
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