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Crab Claws

March 25, 2009

Bromine is what makes the tips of crab claws extra tough.

Transcript

BOB HIRSHON (host):
Why crab claws are extra tough…I’m Bob Hirshon and this is Science Update.

Pick up a Dungeness crab and you’ll see a translucent material on the tips of its legs. It’s the same material that physicist Robert Schofield of the University of Oregon saw on the claws of a striped shore crab he found on the beach. When he analyzed the material in his lab, he found it contained a high concentration of a heavy element called bromine. Schofield says the bromine makes the material in the claw tips ten times more fracture resistant than the rest of the shell.

SCHOFIELD (University of Oregon):
Generally an organism will trade off fracture resistance for hardness. And so this is something that is both hard and very fracture resistant.

HIRSHON:
Fracture is a big problem for small animals like crabs, ants and scorpions. So over time, they’ve evolved tough outer shells to protect against it. I’m Bob Hirshon for AAAS, the science society.