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5 December 2013 11:26 am ,
Vol. 342 ,
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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A Nose for Survival
26 January 2005 (All day)
The robber crab is the world's largest land-living arthropod, weighing up to 4 kilograms, and it steals anything it can carry away in its formidable pincers. That's not the only amazing thing about the crab, say biologists. The crab evolved the ability to smell on land, just like insects do. "This is a really cool study," comments Leslie Vosshall, a molecular biologist at Rockefeller University in New York.
When the ancestors of robber crabs first walked out of their watery environment to live on land, their sensory equipment needed a makeover. The olfactory receptors on the antennae of marine crabs detect soluble, water-loving molecules. A landlubbing crab must zero in on molecules that waft through the air.
Bill Hansson, a chemical ecologist at the Swedish University of Agricultural Sciences in Alnarp, Sweden measured the electrical activity of olfactory neurons in the short antennae of robber crabs at Australia's Christmas Island while puffing scents over these sensory organs. Results of the tests indicate that the electrical activity in response to certain odors is the same in robber crabs as in insects.
This translates into similar senses of smell. Like insects, robber crabs are able to detect carbon dioxide, likely an adaptation for locating decaying meat, which releases copious amounts of the gas. Robber crabs also seem to have a high sensitivity for dimethyldisulphide, and specifically dimethyltrisulphide, which are the same carcass odors that attract insects to animal remains. The researchers report their results in today's issue of Current Biology.
Hansson calls the robber crab's development of a bug's nose "a great example of convergent evolution." He adds, "The robber crabs have reinvented their smell for land so remarkably that they can even smell water."