Dishonest Crabs
by Collin
When I hear dishonesty I think of lying. It turns out that animals can lie, too. When I hear that, I think no way, but scientists from Australia have found out that there is dishonesty in the animal kingdom. The dishonest animal is only two centimeters across, the fiddler crab.
The fiddler crab has one giant claw which it uses to attract mates and fight rivaling males. If the big claw is lost it can always grow a new claw. This is where the lying comes in. During the growth of the claw, the crab’s body says there is a “cheaper” way. They make the claw bigger but they also make it lightweight and toothless. Dr Simon Lailvaux of the University of New South Wales says that the interesting thing is that other males can’t tell them apart. Before a fight the crabs display their big claws which is important to the process.
The study is important because it helps us understand more about dishonesty among animals. The thing is it is hard to pick up on it. It is hard because dishonest signals are supposed to be hard to catch on to. Lailvaux said “By studying how animals fight we can learn what physiological and performance capacities enable males to win fights, we’re getting closer to identifying which traits are likely to be generally important for male combat.”
Can these crabs lose their claw multiple times and if so do they get weaker each time? Are there other animals that can bluff in a similar way as the fiddler crab? How are fiddler crabs able to re-grow their claws? Can this be used to help humans?
November 18th, 2008 at 7:59 pm
Cool post collin. There are other kinds of animals that can lose their limbs. Varities of lizards can lose part of or their whole tail. They do this as an escape mechanism to speed up their movement or to get a preditor to lose its grip on the lizard. Losing this is very harmful to the lizard because over half of it’s fat reserves are in it’s tail. It is also likely to die within a two to three weeks after losing it. Could fiddler crabs also be harmed the same way?
http://www.essortment.com/all/lizardpet_rcpl.htm
November 18th, 2008 at 8:28 pm
This a good post Collin! I was actually in the middle of writing on this same topic before I saw you beat me to it. Because I was writing about this, I noticed some inncorect information. The fiddler crab originaly sends dishonest signals while on his first big claw not second. The crab makes his claw look strong and deadly, when actually it is weak and puny. Also, when a crab rebuilds a lost claw, the claw will either be made lighter and weaker( like you mentioned) or it will rebuild it the right way, full reconstruction. This varies, probably based on the crabs food supply.
http://www.sciencedaily.com/releases/2008/11/081111203501.htm
November 19th, 2008 at 1:10 pm
This is cool, Collin. According to this website, fiddler crabs reabsorb their shells rather than shedding them as they grow. (http://www.tpwd.state.tx.us/huntwild/wild/species/fiddler/) And this website says “During mate searching, females do not discriminate against males with low-mass, regenerated claws, indicating that they are deceived as to the true costs males pay to produce sexual signals. Up to 44% of males in natural populations have regenerated claws, a level unanticipated by current signalling theory.” (http://www.jstor.org/pss/2665754)
November 20th, 2008 at 8:37 pm
This is a good post. I found that the fiddler crabs can regrow the legs either tha hard way, making them stronger or the easy way, making them weaker, depending on the crab. Other than the lizard, some sea stars can regrow their limbs as well, but most of the time the limbs are not lost on purpose. Here is a video of two male fiddler crabs fighting: http://video.google.com/videosearch?hl=en&q=fiddler+crab+video&um=1&ie=UTF-8&sa=X&oi=video_result_group&resnum=4&ct=title#
November 23rd, 2008 at 4:18 pm
Nice post Collin, when I was little my sister and I were afraid of the crabs because they looked so threatening, now I’m kind of disappointed in the creatures. I turns out that fiddler crabs aren’t the only animals that use “deception” to fool rival makes for mates. This website (http://www.pbs.org/wgbh/nova/camo/mating.html ) talks about a bunch of animals that use trickery, like the cuttlefish, who, by changing color will disguises itself as a female and slip right past the dominant male to discreetly mate right under his nose.