Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Fiddler crabs reveal honesty is not always the best policy

Dishonesty may be more widespread in the animal kingdom than previously thought.

A team of Australian ecologists has discovered 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. Published this week in the British Ecological Society's journal Functional Ecology, the study is the first direct evidence that crabs “bluff” about their fighting ability.

The signals animals send each other about their fighting prowess - and the honesty of these signals - is a long-standing problem in evolutionary biology. Despite their size - they are just two centimetres across - fiddler crabs are ideal for studying dishonesty in signalling. This is because males 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.

According to lead author of the study, Dr Simon Lailvaux of the University of New South Wales: “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.”

Dr 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. 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.” Lailvaux explains.

The study is important because it helps shed light on an issue - dishonesty - that is by definition hard to study. “One of the reasons we don’t know a huge amount about dishonesty is because it’s tough to pick up on it. Dishonest signals are designed to be difficult to detect, so to have a system like fiddler crabs where we’re able to do experiments and test hypotheses about dishonesty is pretty cool,” he says.

The results also have important implications for individual reproductive success and survival, as understanding the mechanisms and consequences of dishonesty is essential to uncovering the full story of how these and other animals live, die and reproduce.

According to Lailvaux: “By studying exactly how animals fight, and 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. Honest signalling is important for several reasons, primarily because it’s important that fights don’t always escalate into bloody violence. Fighting can be costly in terms of time and energy, and it’s in an individual’s best interest to avoid risking being injured in a fight, so one of the reasons why we think honest signalling has evolved is because animals need to have a diplomatic option for settling disputes, as opposed to duking it out with every male that comes along. If there’s a way for individuals to assess beforehand which males they are likely to lose to in a fight and which ones they are able to beat, then that allows them to plan accordingly.”

Fiddler crabs live in mangrove swamps and mudflats. There are around 100 species worldwide. Despite their propensity for dishonesty, the name fiddler crab comes from the fact that while waving their big claw to attract females they look like they are playing the violin.

Simon P Lailvaux, Leeann T Reaney and Patricia R Y Backwell (2008). Dishonesty signalling of fighting ability and multiple performance traits in the fiddler crab Uca mjoebergi. Functional Ecology, doi: 10.1111/j.1365-2435.2008.01501.x, is published online on 12 November 2008.

Becky Allen | alfa
Further information:

More articles from Ecology, The Environment and Conservation:

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

nachricht Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Oasis of life in the ice-covered central Arctic

24.10.2016 | Earth Sciences

‘Farming’ bacteria to boost growth in the oceans

24.10.2016 | Life Sciences

Light-driven atomic rotations excite magnetic waves

24.10.2016 | Physics and Astronomy

More VideoLinks >>>