Crayfish win most fights on posturing

Crayfish use bluff to make their opponents back off from a fight, pretending they are stronger than they really.

Melbourne: While they live up to their image
of aggressive creatures, more often than not Crayfish use
bluff to make their opponents back off from a fight,
pretending they are stronger than they really.

According to a report, Crayfish would lose a
fight if they were called on their bluff.

"Most male crayfish are extremely aggressive and can fight
over just about everything including females, food and
shelter," said Queensland University researcher Robbie Wilson.

Their principal weapons are their two front claws, which
are capable of grabbing and throwing the opponent around,
ripping off a claw or even killing. It`s amazing to witness a
fight. It can go on for as long as an hour," Wilson said.

He said but most crayfish disagreements are sensibly
settled before it reaches this stage, by crayfish sizing each
other up.

For example, in one ritual, a crayfish will lay down his
claws while his opponent taps and rubs them.

After this, one crayfish usually backs off in the belief
that they are no match for their opponent`s apparent strength.

But, Wilson and his co-author of Arizona State University
have found that crayfish can bluff their opponents.

They studied the interaction of about 70 crayfish and
tested the actual strength of their claws by measuring the
force with which they pinched two pieces of metal together.

The researchers found that the size of a crayfish`s claws
does not reflect its actual strength. Some crayfish in their
study displayed large claws but had very little muscle power.

"We call this dishonesty. They were displaying to others
that they were strong, high-quality males, but in actual fact
they were cheating. They were actually weaker than what they
were actually displaying," Wilson said.

"Unlike soft-skinned humans whose muscles are on display
for everyone to see, crustaceans` hard shell, or exoskeleton,
is particularly good at hiding how strong they are. It`s like
putting a shell around a human arm and you have no idea how
strong the person is until they start punching you," he says.

Given that 80 per cent of disagreements are settled at the
sizing-up stage, this leaves a lot of room for deception.

As well as some large claws actually having very little
strength due to a lack of muscle, some small claws can be
stronger than larger ones.

To add to this complexity, the two front claws on a
crayfish can differ in size and the larger claw may be
stronger, weaker or the same strength as the smaller claw.

"It`s very difficult for an opponent to actually know the
animal`s overall strength but also which is going to be the
stronger claw. But the fact that it`s also costly if you get
your bluff called limits the evolution of deception. If you do
get figured out, you get severely punished," he says.


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