The cause of death of Caribbean sea urchins

黑龙江 关军红

Scientists say a small parasite (寄生虫) is the cause of death of many sea urchins in the Caribbean Sea.Sea urchins are simple animals that have long spines(脊柱).

Last year,the long-spined sea urchins,also known as Diadema antillarum,started getting sick.They were losing their spines and their sticky feet were losing their grip on the coral reefs.The loss of so many sea urchins,which eat algae (海藻)that grow on the coral,affected the undersea environment from the Virgin Islands to Puerto Rico to Florida.

Mya Breitbart led a team of scientists who investigated the sickness.She is a marine microbiologist at the University of South Florida.The team presented their study recently in the scientific publicationScienceAdvances.“The case is closed,”Breitbart said.

The scientists compared the sick urchins to healthy ones and determined a single-celled parasite was to blame.Ian Hewson is a marine disease researcher at Cornell University in the state of New York.He said the team ruled out bacteria or viruses.

But the team did see single-celled organisms called ciliates in the sick urchins.The scientists then put a group of healthy sea urchins grown in a laboratory in a tank with some of the parasites.Six of the 10 urchins in the tank later died.The scientists are now working to find a way to prevent future losses.They do not have a treatment for the sea urchins,but they are hoping to learn how the parasites spread so they can stop them.

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What causes the death of many sea urchins in the Caribbean Sea according to the text?