Thousands of red crabs swarming in low-oxygen waters off the coast of Panama have been captured on video during a recent diving expedition. The crabs were identified by DNA as Pleuroncodes planipes, or Tuna Crabs, which have never been seen in waters so far south.

The lead author, Jesús Pineda, said “when we dove down in the submarine, we noticed the water became murkier as we got closer to the bottom.” He continued on to say “all of the sudden we saw these things. At first, we thought they were biogenic rocks or structures. Once we saw them moving – swarming like insects – we couldn’t believe it.”  

The researchers believe the crabs were seeking refuge from predators in the low-oxygen waters.

Original research paper published in PeerJ on April 12, 2015.

Names and affiliations of selected authors

Jesús Pineda, Biology Department, Woods Hole Oceanographic Institution, Massachusetts, U.S.A.