Unusually harsh winter temperatures in much of the United States have had a tragic effect on one of Florida's most oddly charismatic animals, killing up to 5 percent of the state's endangered West Indies manatees.

A record 280 or more manatees have already died this year from "Florida frostbite" and other illnesses related to exposure to cold, CNN reports. According to marine biologist Andy Garrett, who works for the state's Fish and Wildlife Conservation Commission,

when water temperatures dip below 68 degrees Fahrenheit, these subtropical animals simply can't cope with the cold. Last month, Florida's water temperatures dropped as low as the 40s. While manatees are round and plump like seals and other marine mammals, their fat is not designed to insulate them from the cold.

Taking Refuge Near Power Plants
Compared to their relatives in the Caribbean, West Indies manatees spending the winter in Florida are already "at the marginal edge of their habitat, and are always susceptible to the cold," CNN says. Hundreds have taken refugee near Tampa Electric Co. and Florida Power & Light power plants, where water discharged into rivers and canals keeps temperatures high. Dr. Martine de Witt at the state wildlife conservation commission's necropsy lab in St. Petersburg says she's seen a surprisingly high number of full-size adults succumbing to the cold.

"That is a very bad sign," she said. The cold water shuts down their internal systems. Many were unable to eat; others drowned because they were unable to breathe. Garrett and de Wit believe that this may just be the beginning. They fear that more manatees will die during the spring, unable to recover from the trauma of Florida's deep freeze.