Perhaps no other star fish receives more attention than Crown of Thorns. This attention is not necessarily born from love. The insidious Crown of Thorns are voracious predators of hard corals. The Crown of Thorns (COTs) could reproduce rapidly and literally mow down large tracks of coral within a short period of time.
The method of destruction employed by the COTs is a gruesome sort of beauty and the beast story. Like all sea stars, the bottom of the COT is made up of hundreds of suction tentacles. As the COT moves across the hard coral surface (covered with thousands of holes each being the home built by one small coral animal called a polyp) the COT adroitly aligns one suction tentacle over one of the coral holes and sucks the little coral polyp out of its home and eats it. An efficient COT can get hundreds of its tentacles working in unison on individual holes and wreak havoc on a large coral structure in just a few minutes leaving behind an empty and dead coral carcass.
Protecting the corals
The NoaNoa reef has never suffered from huge quantities of COTs and since the local government appointed me as the guardian of the NoaNoa Marine Sanctuary we made sure it won’t happen now. When we snorkel around the reef daily and always on the lookout for anything amiss. When we spot a COT, we are determined to remove it from the reef but that is not always easy to do.
Swimming down deep to reach the COTS is the easy part but once there I can’t just grab it because the top side of the COT is lined with poisonous thorns while the hundreds of suction tentacles keep it firmly glued to the coral surface. Tempting as it may be, I cannot smash the COT with a rock or cut it with a knife. If I did the COT would instantly release thousands of eggs into the sea. The COT must be treated gently, taking care not to hurt or alarm it. Sometimes, if I am close to shore, I can find 2 large, dead, plate or antler corals with which I can use one piece to slide underneath the COT while using the other piece to trap the COT from the top. Then, very carefully swim towards the shore while the COT squirms and wiggles its many legs covered with poisonous thorns towards my hands. Inevitably I have to release the COT and get a new grip on it every minute or 2 to prevent getting stung by the thorns. Once on the shore the COT dies quickly.
Most of the time I am far from the shore and have to mentally mark the underwater location of the COT and then swim a kilometer or 2 back to the Beach Bar where I can arm myself with long cooking tongs and an old rice sack before swimming back to the COT. Usually the COT is still in or near the same spot, sometimes the COT can’t be found.
An Ongoing battle
The Great Barrier reef has been battling COTs for years and the Australian marine biologists invented a devise which looks similar to a cattle prod (long narrow tube, pointed at the end) whereby the swimmer can simply push the sharp end of the tube into the COT thereby injecting a dose of acid into the COT. The acid effectively prevents the COT from releasing its eggs and renders death shortly thereafter. In locations infected by thousands of COTs this sort of device came in very handy with a quick kill and no need to remove the dead COTs. Numerous other nations purchased these devices as part of their effort to control the COTs but some of the Australians marine biologists started noticing a troublesome pattern.
The troublesome pattern was this: numerous seemingly spontaneous releases of eggs from thousands of COTs. As the biologists searched for an explanation the pattern became clear. As large populations of COTs were attacked by the acid injection, nearby populations that were not under attack would release their eggs. Long story short: Somehow the COTs could sense the destruction of their species nearby which caused the unharmed COTs to release their eggs. Needless to say, the acid method is not used much anymore. The best method of COT control has reverted to tongs and a sack.
Many Marine Biologists have explained to me that COTs in a reef is not really a bad thing, it is just a fact of a natural eco system. I’m not comfortable with this explanation. The Conch is the primary natural predator of the COT and Conch are now very rare. Too many tourists are willing to buy the beautiful Conch shells and too many locals are happy to capture the Conch to make a nice soup and then sell the shell for a good chunk of cash. The main natural predator of COTs is gone but the COT has a new predator in the NoaNoa reef: Me and the NoaNoa Team.
Years ago, I would collect 4 to 6 COTs per month in the NoaNoa reef. Now I collect about 1 every 3 or 4 months. For now, it seems, we have the situation under control but I know that close observation must continue since the reproduction abilities of the COT are so effective and rapid. Don’t worry about me, I enjoy my work.
A B