Diving scientists record 'cloud' of thousands of swarming crabs

Researchers 'have no idea' why red crabs off Panama might be behaving in such a way, says a biologist: 'Nothing like this has ever been seen'

Descending in a submersible in waters off Panama, scientists noticed something strange happening near the seafloor. It was a drifting fog of sediment, disturbed by something below. Diving deeper, the scientists found the cause: crabs, thousands of them, swarming in a way never before recorded.

"We just saw this cloud but had no idea what was causing it," said Jesis Pineda, a biologist at Woods Hole Oceanographic Institution in Massachusetts and the lead author of a paper on the crabs published on Tuesday.