ReefQuest Videolog - Day 3 - The DIVE!

We we are finally ready for our first dive. Join us with Diver Chris Doherty and the crew of Lahaina SNUBA for our first underwater exploration of the reef. During this dive we discovered a "Crown of Thorns" starfish which is a predator to the coral that was imported to Hawaii from Australia. This starfish eats the Coral. We could see dead coral around the starfish. The crown of thorns can grow from the size of a grain of sand to the size of a dinner plate. The sharp thorns on the sides of the tentacles resemble thorns, making a crown shape, hence the name, Crown of Thorns. An exceptionally large crown of thorns can grow to be the size of a car tire. Divers kill these predators by injecting the starfish's own stomach acid into each of their many legs. If even one leg is missed the sea star can live on. Before overpopulation, crown of thorns kept the fast growing coral from overpowering the slower growing coral. It then proceeds to destroy the coral. It has become a dire threat to the Great Barrier Reef and our reef. If accidentally touched or stepped on by humans, the starfish's long spines are capable of pricking and stinging, inflicting great pain that can last for hours, as well as nausea and vomiting. Frequently, the area around the puncture turns a dark blue and begins to swell. The swelling may persist for a number of days or weeks. Remnants of the spine(s) may be left imbedded in the skin, which must be completely removed.

If you try to cut the starfish it grows into more starfish! The only way to kill it is by a few natural predators. Few animals in the sea are willing to attack the spiny and toxic crown-of-thorns starfish, but surprisingly, some sea creatures prey on them. Notable predators of Ancanthaster planci include the Giant Triton, the harlequin shrimp, a species of worm, and various reef fish which feed on larvae or small adults. Recently, large solitary coral-like polyps of the genus Pseudocorynactis were observed to prey on the crown-of-thorns starfish. It is quite likely that the decline of these predators (through overharvesting, pollution, etc.) has been a factor that led to the rise in the population of the starfish, making outbreaks more likely to occur.