Bacteria-Farming Crab

Researchers have discovered that a certain species of crab apparently actively grows bacteria on its arms and eats them as its main source of food. From National Geographic

In 2006 scientists uncovered another species of yeti crab, K. puravida, living in cold, methane-seeping fissures about 3,300 feet (1,000 meters) deep near Costa Rica.

K. puravida regularly waved its claws slowly and rhythmically, puzzling scientists…

One early explanation for the behavior was that the crabs were trying to keep others at a distance.

But chemical analysis of K. puravida‘s tissues and the bacteria dwelling on its silky arms revealed the crustaceans dine mostly on these bacteria.

Video taken by submarine then revealed that the crabs harvest their crops using highly specialized hairy mouth appendages, which scrape the bacteria off their arms…

Researchers now suggest the claw-swaying helps wash nutrients over the bacteria, essentially fertilizing them…

It remains uncertain whether the yeti crab’s hairy appendages might help detect currents in the water. If so, the appendages may help crabs identify the sources of the nutrients that sustain their microbe “farms.” …

Deep-sea shrimp and other animals had been found with bacteria growing on them before, but this is the first clear evidence of a deep-sea animal farming its bacteria, said Thurber, whose study appeared November 30 in the journal PLoS ONE.

“This shows us how little we know about the deep sea, and how much more we might find and have to protect, as exploration for resources expands into these areas.”

That’s pretty fascinating behaviour; I wonder if this crab’s intelligence is unexpectedly high, or if this behaviour arose very accidentally and is now ingrained? It also reminds me of ants that farm aphids, an even more incredible behaviour in its resemblance to humans. These ants protect aphids and store aphid eggs, even taking aphid eggs with them when they start new colonies. They apparently stroke the aphids to “milk” honeydew out of them, which they then consume. And you thought we were the only farmers…

Anyway, as the last quoted paragraph states, this just reaffirms how much we have to learn about the deep sea and the natural world in general. It’s an exciting world out there!

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