Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Urine trouble

15.04.2002


A crayfish’s urine scares off its enemies.


The left-hand crayfish fans green urine at its opponent
© T. Breithaupt



A well-timed blast of urine is the key to winning a crayfish fight, say researchers. The chemical aggression intimidates opponents into backing down.

Ecologist Thomas Breithaupt injected freshwater crayfish with a dye that made their urine glow green. He and his colleague Petra Eger staged fights between blindfolded crayfish (Astacus leptodactylus), to replicate the animals’ nocturnal habits1.


The eventual winners were more likely to urinate than the losers. "Urine release is saying ’hey, pay attention: this is a dangerous guy’," says chemical-communication specialist Jelle Atema of Boston University.

A crayfish smelling another’s urine may be able to gauge its sex, diet, state of health and whether it has recently lost its protective armour by moulting. Only animals in top condition, or those extremely determined to win, can afford to expose their vulnerabilities by broadcasting such signals.

This probably explains why crayfish do most of their urinating in combat situations. "It’s not a good idea to inform your whole social environment about the mood you’re in," says Breithaupt, who works at the University of Hull.

Crayfish probably also add pheromones to the brew, advertising their strength and aggression, much as deer use their musk glands, says Atema. The exact chemical make-up of the urine is unknown - but Breithaupt hopes to find out.

Fight club

Freshwater crayfish fight a lot. They live in dense groups of up to 20 individuals per square metre, and squabble over food, shelter and mates.

Brawls involve a ritualized escalation of violence - from posturing, to gripping, arm wrestling and finally attempting to wrench each other’s limbs off. Urination increases as the animals become more aggressive, the researchers found.

Chemical signals in the urine tell each party how likely it is to win, reducing the number of extreme fights. If urine release is blocked, fights are longer and more violent.

Crayfish waft the glowing urine towards opponents with their gills. "As far as I know, this is the first time that anyone’s seen chemical communication underwater," says Breithaupt, although the water probably hums with such messages.

But chemical posturing still needs something to back it up, says Atema, and most encounters do get physical. "Violence is always the reinforcer."

References

  1. Breithaupt, T. & Eger, P. Urine makes the difference: chemical communication in fighting crayfish made visible. Journal of Experimental Biology, 205, 1221 - 1231, (2002).


JOHN WHITFIELD | © Nature News Service

More articles from Life Sciences:

nachricht Nesting aids make agricultural fields attractive for bees
20.07.2017 | Julius-Maximilians-Universität Würzburg

nachricht The Kitchen Sponge – Breeding Ground for Germs
20.07.2017 | Hochschule Furtwangen

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

Leipzig HTP-Forum discusses "hydrothermal processes" as a key technology for a biobased economy

12.07.2017 | Event News

 
Latest News

Researchers create new technique for manipulating polarization of terahertz radiation

20.07.2017 | Information Technology

High-tech sensing illuminates concrete stress testing

20.07.2017 | Materials Sciences

First direct observation and measurement of ultra-fast moving vortices in superconductors

20.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>