It’s like a scene out of a sci-fi movie — thousands, possibly millions, of king crabs are marching through icy, deep-sea waters and up the Antarctic slope.

‘They are coming from the deep, somewhere between 6,000 to 9,000 feet down,’ said James McClintock, Ph.D., University of Alabama at Birmingham Endowed Professor of Polar and Marine Biology.

Shell-crushing crabs haven’t been in Antarctica, Earth’s southernmost continent, for hundreds or thousands, if not millions, of years, McClintock said. ‘They have trouble regulating magnesium ions in their body fluids and get kind of drunk at low temperatures.’

But something has changed, and these crustaceans are poised to move by the droves up the slope and onto the shelf that surrounds Antarctica. McClintock and other marine researchers interested in the continent are sounding alarms because the vulnerable ecosystem could be wiped out, he said.

Antarctic clams, snails and brittle stars, because of adaptation to their environment, have soft shells and have never had to fight shell-crushing predators. ‘You can take an Antarctic clam and crush it with your hands,’ McClintock said. They could be the main prey for these crabs, he said.

Loss of unique mollusks could jeopardize organisms with disease-fighting compounds, McClintock said. Sea squirts, for example, produce […]