for National Geographic News
Predatory starfish are swarming over one of the world's most diverse coral reef ecosystems, researchers announced, threatening the health of reefs throughout the Indo-Pacific region.
Crown-of-thorns starfish, named for the long spines covering their bodies, feed on corals by spreading their stomachs over the animals living inside, then secreting enzymes that liquefy the corals' tissue.
"They prefer certain species and take them first, then they'll eat the others later," said Alison Green, a marine scientist with the nonprofit Nature Conservancy.
The starfish are found naturally throughout the Indo-Pacific. But a recent survey of reefs off the Indonesian island of Halmahera revealed that the numbers of the predators in some areas are double those that exist in a healthy reef.
Halmahera, the largest island in Indonesia's Maluku group, lies within the "coral triangle," which has been described as a global center of marine biodiversity.
The triangle spans eastern Indonesia, parts of Malaysia, the Philippines, Papua New Guinea, Timor, and the Solomon Islands (see a map of the region).
The localized starfish outbreak, experts say, could be an early warning of more widespread reef decline.
"Imagine the most beautiful coral reef with lots of three-dimensional structure, lots of color, and lots of fish," Green said.
"Then [imagine] the same place, except that it is dead, covered in black algae, and the fish are gone. Crown-of-thorns can do that."
Andrew Baird is a scientist with the Australian Research Council's (ARC) Centre of Excellence for Coral Reef Studies and James Cook University.
He was part of the starfish survey team, jointly led by the ARC center and the New York-based Wildlife Conservation Society.
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