BioEd Online

A blind white crab bristling with hairs has been wrested from the deep, named, and slotted into the family tree of crustaceans.

It was a beautiful March day, more than 1,000 kilometres south of Easter Island. A team organized by evolutionary biologist Robert Vrijenhoek of the Monterey Bay Aquarium Research Institute (MBARI), in California, was prospecting for hydrothermal vents gushing hot water from the sea floor.

"The sea was like a lake," says Joe Jones, a deep-sea geneticist at MBARI. A submersible called Alvin surfaced, and Jones's colleague Michel Segonzac, of the French Research Institute for Exploitation of the Sea in Brest, crawled out of it. Using Alvin, Segonzac had netted a white crab he thought might intrigue Jones from the periphery of a newfound hydrothermal vent.

"It was huge," recalls Jones. "It was seven inches long, and eyeless and hairy. We all realized it was really different, but we didn't have any specimens to compare it with, or DNA techniques on board to analyse it."

Not for eating

Several months later, Jones and his colleagues were able to sit down and try to place the creature that they had named the 'yeti crab' into a family tree. It became clear that the 15-centimetre-long crustacean was distinct enough from its known relatives to be the first member of a new family: Kiwaidae¹. Kiwa is the goddess of shellfish in Polynesian mythology. They gave the crab the proper name of Kiwa hirsuta.

When pictures of the specimen were shown at the International Crustacean Conference in Glasgow in July 2005, Jones began to realize just how big the find was. "A kind of murmur went around the room," he said.

The function of crab's 'hairs', which feel like toothbrush bristles, is still unknown. Rafael Lemaitre, chair of invertebrate zoology at the Smithsonian's National Museum of Natural History in Washington DC, and a crustacean expert, thinks they might be used to comb edible materials from water or mud. "The hairs are almost like feathers," he says. "They have secondary and tertiary branches. That facilitates all kinds of things sticking to them."

The hairs seem to be covered with, or even made up of, filamentous bacteria. Whether the crabs eat the bacteria or use them for another purpose remains to be seen.

Lemaitre calls the find "amazing", but is not so sanguine about its gastronomic potential. "It probably does not have a lot of muscle to sink your teeth into, and things that live near hydrothermal vents that contain sulphur are probably not very tasty."

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