Antarctic Crab Farms Hair

This Antarctic crab gets my vote for the most bizarre summer lifestyle. The crab grows in hydrothermal vents, part of the ocean floor where volcanic heat drives hydrogen-rich molecules up through a super-heated spring. Hydrogen sulfide, methane etc. Bacteria can oxidize these molecules for food; such bacteria inhabit the guts of tube worms and giant clams that have evolved to support them, and can eat nothing else.

But the crabs have a different twist–they farm the vent bacteria on the hairs of their claws. Their claws look furry from all the bacteria-covered hair; and the crab scarfs off the bacteria.

According to the journal, the bacteria actually fix CO2 like plants do. Instead of photosynthesis, the bacteria oxidize reduce molecules such as methane. There is plenty of oxygen at the ocean floor, from phototrophs at the ocean surface; the water is so productive that excess oxygen reaches the floor. That won’t always be true though, as human-made “dead zones” are expanding throughout the ocean.

In order to survive, the crab needs to stay within a narrow range of habitat between the vent (400 degrees C) and the near-freezing water at the bottom. So the crabs crowd together, jockeying for the best spot. An epic survival story, for sure.