© Adam Li / NOAA Photo LibraryPilot whale.
It's not yet clear why more than 16 pilot whales became stranded in the lower Florida Keys on Thursday, but the list of possible reasons is long -- and includes the whales' social nature.
Pilot whales live in groups called pods that consist of between 15 and 50 animals, and mass strandings like this one have happened before. Most recently, in 2003, about 25 pilot whales became stranded in the Keys, according to Anne Biddle, media relations director for the Marine Mammal Institute, which is responding to the stranding.
"They tend to strand in pods, they stick together, if one is sick, the whole pod is going to strand," Biddle told LiveScience. The whales are stranded in shallow water, and veterinarians are assessing them to determine if all or a couple are sick, she said.
Pilot whales are toothed whales that can grow to be between 14 and 17 feet (4.3 to 5.2 meters). They live in warm, tropical waters, according to Biddle.
There are many potential causes -- including diseases, parasites, loud noise, toxins or simple confusion -- so figuring out what is responsible for the mass stranding can be challenging, according to Chris Parsons, a professor at George Mason University who has tracked mass whale strandings around the world.
