Crown-of-Thorns Cleanup!

Martin & I went diving on Sunday; but it was anything but the lay-back-and-relax, let-the-current-carry-you, scenic tour we're accustomed to here in the world of Bunaken diving... we were on a mission to rid the local reef of the insidious "Crown-of-Thorns" Starfish (COTS). Armed with nothing but bamboo tongs, we scoured the reef for several hours.

This colourful, spiky critter naturally occurs in tropical coral reefs, but is very invasive in the reef ecosystem... more so in many areas because their natural predator populations (especially the Napoleon (Humphead) Wrasse fish and a Triton seashell) are declining due to exploitation and over-fishing. Could a change in climate also be a contributing factor? I'm not sure, but I wouldn't rule it out entirely.

So what do they actually do to the reef? Well, they basically eat it alive. The COTS feed on coral polyps (you all know coral is 'animal' not mineral, or plant, as most people believe, am I right?). They use their suction-cup feet to manoeuvre their way over the reef, then they basically extrude their stomach outside their exoskeleton (body) to cover a section of coral. The stomach then releases its digestive enzymes and they go to work!

Even though they are causing damage to the reefs, I find reason to marvel at COTS. They are voracious predators... one individual can consume up to 6 square meters of living reef in a year!

Anyway, because these little devils are nocturnal feeders and tend to tuck themselves in holes and under the reef to stay out of the sunlight during the day, it was no mean feat collecting them up! The local guys here say that for every one that we found during the day there are surely 4 more that we could find if we hunted at night.

For various reasons we didn't. Although it wasn't the official reason given, I have a feeling that the danger factor was the deciding factor. The long spines contain poison, which inflicts great & long-lasting pain if you get pricked. A friend of one of the local men we dove with was 'bitten' (that was his terminology) and became violently ill for a couple of days (including nausea and vomiting). Just another minor marine terror that I find myself in close proximity with!

The haul.