Marine biologists inside a submersible vehicle under the deep waters of Panama spotted something strange near the seafloor. After a fog of sediment lifted, it was clearly disturbed by something deeper down below where they uncovered thousands of crabs swarming in such a manner that has never been seen before.
According to biologist and lead author of this new study, Jesús Pineda from the Woods Hole Oceanographic Institution in Massachusetts, at first there was this cloud but we have no idea what is causing this. We initially thought it was biogenic rocks or structures and when we saw it moving like a swarm of insects, we could not believe what we saw.
Pineda describes the cloud of crabs as nothing ever seen before, as this was composed of a very dense swarm found at the bottom, where they also have no idea why they are doing this. He then investigated, searching for similar behavior in different crab species, lobsters, shrimp and other crustaceans and marine animals whose habitat is near the bottom of the ocean but he did not find anything.
During that time, the team of researchers were studying the ecosystem of the Hannibal Bank Seamount, in the Pacific coast of Panama.
After DNA analysis, these multitude of crabs are identified as Pleuroncodes planipes, also commonly known as the red crab for its coloring or the tuna crab since tuna is their favorite diet. Each individual measures just about one to five inches long which are initially thought to be native only to the southeastern coasts of California and Mexico.
Pineda adds that this new discovery of crabs swarming deep down south and in very massive numbers is very unusual. The swarm was located some 1,200 feet below the surface near a region filled with hypoxic water, that possesses extremely low levels of oxygen, that makes it hard for marine species to survive. The crabs can also be seen in other hypoxic regions where researchers suggest that their ability to survive in this extreme environment can allow them to take sanctuary from other predators.
Researchers also believe that studying further this region can provide further crucial insights for climate change research since warming oceans are causing more low oxygen environments, killing coral and endangering other marine ecosystems in more shallow regions.
Red crabs are also known to live in massive schools up and down a water column where they are believed to feed in higher water during the night and swarm together in great numbers during the day according to Pineda. This new study is published in the journal PeerJ.