Lobsters play biological violins

May 08, 2001

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 of long, stiff, spine-encrusted antennae, and several faded scratches on Patek's arms bear witness to the antennae's effectiveness as defensive tools.

During the molting period, however, the spiny lobsters' antennae and shell are too soft to protect them against predators. Instead, the lobsters must rely on scare tactics - sound - to drive predators like sharks, grouper, and triggerfish away. A sound-producing mechanism that relied upon hard surfaces would be of little use during this vulnerable stage. This suggests that the lobsters' soft-tissue-based sound structures are an evolutionary response to predation, Patek said.

"Organisms face many mechanical problems," Patek said in an interview. "In this case, lobsters are able to make sound without relying on hard parts, and therefore they can make sound when their exoskeleton is softened and they are most vulnerable to predation."

Patek said future research might turn up other examples of animals using the same violin-like "stick-and-slip" method to produce sound. She added that she hopes her research will spur others to investigate sound-producing mechanisms and their evolutionary history. Patek's own future includes a three-year postdoctoral Miller Fellowship at UC-Berkeley, where she intends to study the evolution of signals and communication in mantis shrimp.
Note to editors: Sheila Patek may be reached at 919-660-7265, snp2@duke.edu. An image of Patek with a spiny lobster is available at http://photo1.dukenews.duke.edu/pages/Duke_News_Service/lobster as file name lobster.jpg, and a graphic explaining how the sound is produced is in the same folder as lobsgraf.jpg. B-roll video, including an interview with Patek and footage in her laboratory, is available. To preview the video files in MPEG, QuickTime or RealStream formats, contact Cabell Smith, 919-681-8067, cabell.smith@duke.edu. Broadcasters can also contact him to receive a Beta format tape of the video footage.

Duke University

Related Predators Articles from Brightsurf:

Boo! How do mexican cavefish escape predators?
When startled, do all fish respond the same way? A few fish, like Mexican cavefish, have evolved in unique environments without any predators.

Herbivores, not predators, most at risk of extinction
One million years ago, the extinction of large-bodied plant-eaters changed the trajectory of life on Earth.

Bugs resort to several colours to protect themselves from predators
New research has revealed for the first time that shield bugs use a variety of colours throughout their lives to avoid predators.

Jellyfish contain no calories, so why do they still attract predators?
New study shows that jellyfish are an important food source for many animals.

'Matador' guppies trick predators
Trinidadian guppies behave like matadors, focusing a predator's point of attack before dodging away at the last moment, new research shows.

The European viper uses cloak-and-dazzle to escape predators
Research of the University of Jyväskylä demonstrates that the characteristic zig-zag pattern on a viper's back performs opposing functions during a predation event.

Predators help prey adapt to an uncertain future
What effect does extinction of species have on the evolution of surviving species?

To warn or to hide from predators?: New computer simulation provides answers
Some toxic animals are bright to warn predators from attacking them, and some hide the warning colors, showing them only at the very last moment when they are about to be attacked.

Dragonflies are efficient predators
A study led by the University of Turku, Finland, has found that small, fiercely predatory damselflies catch and eat hundreds of thousands of insects during a single summer -- in an area surrounding just a single pond.

Predators to spare
In 2014, a disease of epidemic proportions gripped the West Coast of the US.

Read More: Predators News and Predators Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.