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| Photo of a male fiddler crab Uca from www.arkive.org |
Judging a confident male fiddler crab, one can
be easily captured by its unique, brightly colored, threatening enlarged claw. Fiddler
crabs (Genus Uca) are major
inhabitants of mud and sand flats along estuaries and sheltered coasts in the
tropics and subtropics [1]. They may be small but their claws appear robust and
powerful that you would not even think twice of its combating prowess. Or, should
we?
Australian ecologists discovered this “bluff”
in a group of fiddler crabs. The crabs use their massively enlarged claws for
fighting over turfs as well for attracting females [1]. Once they lose a claw upon battle, they may
grow another one, most of the time a replica of the original. The new claw,
however, is a far cry to how they physically appear. It is lighter and
toothless, rendering them weak and inferior [2].
Fighting ability is measured through major claw
size, claw strength and the ability to resist being pulled from a tunnel. Crabs
size up each other through their major claws, waving them in the air with
surety. This means that physical make-up of the enlarged claw is detrimental in
picking fights [2].
Now, to advertise one’s sex or to incite fight
over territories, a crab will wave its regenerated claw, either up and down,
others sideways, during low tide at territories established around their
burrows [1]. Now, the wave is done and a fight may ensue. Unfortunately, the
potential opponent, which is about to be fooled but is clueless of it, cannot
distinguish the regular, powerful authentic claws from the cheap ones. The
shining, regenerated claw is unfortunately void of any information on its
fighting capacity. The opponent is then deceived and backs off. This remains
true unless the crab with the regenerated claw holds territory and is trumped
by a stronger opponent, revealing his bluff [2].
Knowing that this kind of dishonesty in the
animal kingdom exists may provide an opportunity for ecologists to study
dishonest signals. This discovery can also shed light on the individual
reproductive success and survival among fiddler crabs by a thorough
understanding of dishonesty mechanisms and consequences [2].
To know more about fiddler crabs, visit
SeaLifeBase or come be a collaborator!
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[1] Castro, P., & Huber, M. E.
(2003). Marine Biology (4th ed.).
Boston , Massachusetts
[2] British Ecological Society
(BES). Fiddler Crabs Reveal Honesty Is Not Always The Best Policy.
ScienceDaily. ScienceDaily Retrieved from
www.sciencedaily.com/releases/2008/11/081111203501.htm.
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