Why did those pilot whales in Florida beach themselves?

Twenty-one short-finned pilot whales beached themselves along Florida's Atlantic coast on Saturday, prompting rescue efforts and questions about what drove the creatures out of the water.

"There's 21 whales in total, two have died already of natural causes," said Carli Segelson of the Florida Fish and Wildlife Conservation Commission.

She spoke from Fort Pierce, Florida, on the state's south-central Atlantic coast, where the whales, including at least two calves, were discovered at about 9 a.m. EDT (1300 GMT).

Officials from the U.S. National Park Service, Florida Fish and Wildlife and the National Oceanic and Atmospheric Administration were checking the whales and trying to determine whether they could be coaxed back out to sea, Segelson said.

She said pilot whales, which are considered highly intelligent, are a species that commonly strand themselves on beaches around the globe.

Such incidents have often been blamed on infestations of parasites that affect the whales' brains and their ability to stay on course. They normally stick to deep waters, where they feed on a diet that includes squid and octopus.

"Right now the cause isn't clear," said Segelson.

Male pilot whales, which are normally dark black and larger than their female counterparts, can grow to about 20 feet (6 meters) and tip the scales at as much as three tons. 

(Reporting By Tom Brown; Editing by Xavier Briand)