crown of thorns starfish
The crown-of-thorns starfish is named for the brightly-colored spikes that coat its legs. This starfish can grow up to 16 inches across and has between 12 and 19 legs instead of the usual five -- that’s a lot of spikes!
These spikes hold poison that can cause temporary paralysis at the sting site and nausea in humans. Like other starfish, the crown-of-thorns can regrow arms. At the end of each of these arms is an eyespot that can detect light and darkness, although not color or shape.
Crown-of-thorns starfish are avid eaters of coral, and just one starfish can eat 13 square miles of coral each year. In order to eat the coral, the crown-of-thorns starfish pulls its stomach out of its body to cover the coral, then feeds through tiny hairs called cilia. All that remains of the coral is its white skeleton. Despite being voracious eaters, crown-of-thorn starfish can survive food shortages of up to six months by living off reserves.
Since the 1970s, plagues of crown-of-thorn starfish have been occurring more and more frequently, particularly in Australia's Great Barrier Reef. Scientists are still debating whether these are natural or have been caused by overfishing crown-of-thorn predators.
There aren’t many creatures interested in such a prickly snack, but a few mollusks and fish like the giant triton and the titan triggerfish play important roles keeping crown-of-thorn starfish populations under control.
Learn more about the crown-of-thorns starfish and other fascinating animals at Oceana’s marine encyclopedia.
Guest blogger Jon Bowermaster is a writer and filmmaker. In this post, Jon reports on the state of corals in Bora Bora.
Bora Bora, Society Islands, French Polynesia – I dove last week in the beautiful lagoon that surrounds the tall island to have a first hand look at how the coral reef is doing in this South Pacific resort island. The report is not good.
Descending to 90 feet, it was immediately clear that the reef has been hammered in the past few years. I’ve come here every year for the past decade and have seen incredible change.
I spent most of the morning observing the still-growing reef system just 10 to 30 feet below the surface. Although the waters are warm and magnificently clear, invasive predators and natural disaster have both taken big tolls.
Populations of acanthaster -- also known as the crown-of-thorns starfish – mysteriously arrived in Polynesia in 2006. No one is sure exactly how they got here or where they originated, though invasive species are well known for hitching rides on cargo ships and jumping off far from home. Here in the shallows surrounding Bora Bora – as they have done to reefs on nearby Moorea, Raiatea-Tahaa, Huahine and Maupiti – the predatory starfish have devoured hundreds of acres of coral.