How lying saves crabs' lives

Washington, Nov 12 : A team of Australian ecologists has discovered that crabs 'bluff' about there fighting ability.

They found that some male fiddler crabs 'lie' about their fighting ability by growing claws that look strong and powerful but are in fact weak and puny.

The findings are helping scientists discover more about dishonesty in the animal kingdom.

Male crabs have one claw that is massively enlarged (which they use to attract females or fight rival males) and if they lose this claw during fights they can grow a replacement.

In most species, the new claw is identical to the lost one, but some species "cheat" by growing a new claw that looks like the original but is cheaper to produce because it is lighter and toothless.

"What's really interesting about these 'cheap' claws is that other males can't tell them apart from the regular claws. Males size each other up before fights, and displaying the big claw is a very important part of this process," said lead author of the study, Dr Simon Lailvaux of the University of New South Wales.

Lailvaux and colleagues from the Australian National University measured the size of the major claw in male fiddler crabs, and two elements of fighting ability - claw strength and ability to resist being pulled from a tunnel.

They found that while the size of an original claw accurately reflects its strength and the crab's ability to avoid being pulled out of its burrow, this relationship does not hold true for a regenerated claw.

"This means that while males can gain an idea of the performance abilities of males with original claws from the size of those major claws, regenerated claws don't reveal any information on performance capacities," Lailvaux said.

"Males with regenerated claws can 'bluff' their fighting ability, like bluffing in a poker game. They're not good fighters, but the deceptive appearance of their claw allows them to convince other males that it's not worth picking a fight with them.

"The only time it doesn't work is when regenerated males hold territories, which means they can't go around choosing their opponents - they have to fight everyone who challenges them, and eventually someone will come along and expose their bluff," he added.

The study is published in the British Ecological Society's journal Functional Ecology.

ANI