Sharks have a remarkable gel in their snouts that produces electricity in response to minute temperature changes, enabling the fish to spot heat differences in water that could lead them to prey, a scientist says.
The gel lies in channels beneath the shark's skin which connect pores on the surface with sensors called ampullae of Lorenzini.
These sensors are known to be highly sensitive to electrical fields generated in the water by the muscles of a wriggling fish, perhaps even the heartbeat of a swimmer.
But Brandon Brown, a University of San Francisco physicist, believes the ampullae are also finely tuned to temperature changes, thanks to the thermo-electric gel.
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sensitive to a temperature change of less than one thousandth of a degree C.
When the shark swims into an area where the water has become abruptly colder or warmer, the heat change is transformed into an electrical signal by the gel, which causes the sensors to fire, sending a message to the fish's brain.
Brown's experiment with shark gel samples revealed that the gel delivers 300 microvolts of electricity for every one degree change in water temperature. Previous experiments showed sharks could be sensitive to a temperature change of less than one thousandth of a degree C.
Brown speculates that it helps the predators to locate areas where warm and cold water mix, often bringing up nutrients on which smaller fish feed.
The gel appears to be based on a family of proteins called glyco-proteins. There are many exciting potential applications for a synthetic substitute for the gel, Brown said.
"You could have a form-fitting gel-filled parka, providing battery-operated warmth or, if you are in a hot environment, like a firefighter, the gel could move heat out of your body."
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This article was originally published on page 4 of Cape Argus on January 30, 2003
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