Feeling Out Crayfish Brains

Crayfish use long antennae and short antennules to feel their way around, and scientists are now using the biological sensors to get a better sense of brain function.

The longer antennae help crayfish physically feel out an area, while the smaller antennules help them sniff for food, mates or danger. "They constantly flick their antennules," said DeForest Mellon, a University of Virginia biologist. "It is doing two things that are processed simultaneously in the brain as he flicks: smelling the water, and also sensing motion in the water, which can indicate the presence of food or other things of interest."

Mellon said that crayfish are a good, small test bed to figure out how brain tissue integrates all sorts of different inputs to give a creature an overall sense of its environment. "It’s fertile ground for ongoing research," he said. "The size of an area of the brain devoted to a particular sense gives us a good idea of how an animal perceives the world. It provides insight as to how the world is interpreted by that animal."

About 40 percent of a crustacean's brain is devoted to the sense of smell, which is necessary in dark environments at the bottom of an ocean. Humans, by contrast, use less than 1 percent of their brain (by volume) to pick up scent—but about 30 percent of the human brain is concerned with visual processing.

"Through often very subtle adoption of genetic variations in different animals, evolution has arrived at different solutions to common survival problems," Mellon said.

—LiveScience Staff

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Credit: Dan Addison, University of Virginia