DURHAM, N.C. -- A Duke University graduate student has discovered that spiny lobsters make sound using the biological equivalent of a violin the first time such a mechanism has been found in nature.

"Lots of people have tried to explain how these lobsters make sounds, and most of them were wrong," said Sheila Patek, whose research is reported in the May 10 issue of Nature. "We've never seen this before."

Using an underwater microphone and tiny sensors attached to the lobster's antennal muscles, Patek showed that when a lobster moves its antennae in a certain way, a nubbin of tissue called a plectrum rubs over a file near its eyes, creating frictional pulses of sound. Unlike crickets and other animals that produce sound by scraping a hard "pick" over a ridged "file," a lobster's plectrum is made of soft tissue, and the file's surface is macroscopically smooth. So, although the sound they produce is hardly musical it resembles a cross between a stick dragged across a washboard and a moist finger rubbed on a balloon the underlying mechanism is similar to a violinist drawing a bow across the strings of her instrument.

Since lobsters cannot hear except at very close range, the sounds they make are probably not used to communicate with each other, Patek said. Instead, she said the sounds serve as a defense against predators, which may be startled long enough for the lobster to escape. "If you were reaching down to pick up a sandwich, and it squeaked, you might pause," Patek explained.

Sound-based defense mechanisms are relatively common in nature, Patek said, but the lobster's is unusual from an evolutionary as well as a structural standpoint. Not all lobsters are noisy, only certain species in the Palinuridae, or spiny lobster, family. These lobsters bear little resemblance to the docile creatures found in supermarket tanks; aside from their mottled coloring, their most striking characteristic is a pair
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Contact: Dennis Meredith
dennis.meredith@duke.edu
919-681-8054
Duke University
8-May-2001