July 10 2007
But an international team of researchers that includes an Indiana State University professor is calling natureâ€™s bluff.
A new study to be published in The American Naturalist suggests dishonest signals of strength or fighting ability play a much greater role during disputes than previously imagined, at least among one species of crustaceans.
In nature, individuals often signal their superior strength to rivals to resolve territorial disputes without direct combat, thereby reducing the potential costs of engaging in fights. Male crayfish routinely use their large front claws for intimidation and fighting.
â€œThe size of a crayfishâ€™s claw had everything to do with whether a crayfish would dominate in an encounter," said Michael Angilletta, associate professor of ecology and organismal biology at Indiana State. â€œOftentimes, smaller crayfish would see an individual with a larger claw and they would run away even though it may be an individual with a weaker claw.â€
Angilletta helped analyze data gathered by Robbie Wilson of the University of Queensland, the studyâ€™s main author. While in Australia for unrelated research, Angilletta spent two months doing extensive experiments to confirm the validity of the initial study of 32 slender crayfish.
â€œThe variation in strength is repeatable. You get these really big crayfish that have massive claws. When you get pinched by one, you think itâ€™s going to hurt but it doesnâ€™t hurt at all. Then you get little crayfish with much smaller claws and they can actually hurt quite a bit. For a given size claw, we found a tenfold variation in strength,â€ Angilletta said.
â€œDishonesty during disputes may be far more prevalent than we previously imagined,â€ said Wilson.
As is often the case with such research, answering one question leads to additional questions.
â€œIs this kind of bluffing going on in other species and people just havenâ€™t looked,â€ Angilletta asked.
â€œOur findings also challenge us to come up with a theory that can explain this exception. Hereâ€™s a population of animals that is bluffing a lot and it raises the question, â€˜Why donâ€™t other individuals call their bluff,'â€ he said.
â€œIf youâ€™re playing poker with a bunch of guys and one guy is bluffing constantly, people are going to figure him out. If youâ€™re playing poker and everyoneâ€™s bluffing, then bluffing is never going to work, but crayfish donâ€™t seem to recognize the bluffing. Itâ€™s a puzzle as to how this is maintained in the population.â€
Contact: Michael Angilletta, associate professor, ecology and organismal biology, Indiana State University, firstname.lastname@example.org
Writer: Dave Taylor, media relations director, Indiana State University, (812) 237-3743 or email@example.com
An international team of researchers that includes Michael Angilletta, associate professor of ecology and organismal biology at ISU, has found that bluffing - previously thought to be rare or nonexistent in the animal world - is widespread among crayfish. The study is soon to be published in The American Naturalist.