A Claw Like a Sledgehammer

The December issue of Smithsonian Magazine, in readers' mailboxes today, features this interesting bit of behavior  by mantis shrimps.  The very brief article is by Tom Frail:

NAME: the mantis shrimp *(Neogonodactylus wennerae)*, a coastal crustacean

EATS snails, blasting open their shells with a "raptorial appendage" that is basically a spring-loaded hammer capable of slicing through seawater at 45 m.p.h.

FIGHTS ritual fights with other mantis shrimp to protect its burrow, trading blows to the tail that would shatter mollusk shells and crab carapaces.

LIVES through this punishment because its tail, or telson, dissipates almost 70 percent of each blow's energy.  How? A new study has found that the telson is structured to absorb energy like a punching bag, rather than like a trampoline. And the bigger the telson, the bigger the blow it can take. The finding, says lead author Jennifer Taylor of Indiana University-Purdue University at Fort Wayne, suggests that mantis shrimp in ritual combat may be using information from their tails and raptorial appendages to size up  opponents before deciding how far to take the fight.

Here's a link to a TED talk by researcher Sheila Patek.