Tuesday 15 May, 2001
Spiny Lobster Violinists
Seas, lakes and rivers are in some places alive with noise. Underwater creatures have evolved remarkable ways of generating sound to communicate with each other, and to warn off predators.
New research, outlined in the journal Nature, claims that the spiny lobster produces sound using ‘the stick and slip mechanism’, the same method as the violin. Using organs just under their eyes, spiny lobsters can make quite a din. Science In Action reports.
The spiny lobster is the first known creature to create a novel underwater sound using a frictional method similar to a violinist drawing a bow across strings.
According to new research carried out by Dr Sheila Patek from Duke University in Durham, North Carolina, the spiny lobster scrapes the fleshy end of its antennae, known as a plectrum, against the hard plates under its eyes to produce a pulsating sound with which it wards off predators.
Sound-based defence mechanisms are not uncommon in the animal kingdom. Animals, such as crickets, produce a sound by dragging a hard “pick” over a ridged file – similar to dragging your nail across a combs teeth. However the spiny lobster’s plectrum is made from soft matter and the surface of the shell is smooth, and is therefore unusual, as it is more akin to the mechanism of the violin.
Predator Protection
Dr Patek studied the creatures by using an underwater microphone and tiny sensors attached to the lobster’s antennae muscles. Recognising that lobsters have a short range for hearing sound, and pick up on vibrations, Dr Patek has been led to conclude that the spiny lobster is unlikely to use the resulting screech as a form of communication, but rather to warn off predators.
This tactic has particular significance during the lobsters’ moulting period, when they become more vulnerable to predators as they shed their hard shell in order to grow. Lobsters moult up to 25 times in the first five years of their life and then every year afterwards.
During this period they must rely on their noisy scare tactics to keep predators such as sharks and trigger fish at bay. Dr Patek explains:
‘They want to produce a sound that deters predators and basically by relying on a mechanism that doesn’t use hard parts, like most arthropods do, they can still produce this sound.’
| ‘Sure enough if you hold a lobster that is in the process of moulting that has a very soft exoskeleton it can produce a great burst of sound even though its body is completely soft.’ | |
Rare Stick and Slick Sounds
The “stick and slip” sound mechanism, which Dr Patek likens to running a finger over a balloon surface, is extremely rare in nature. Whilst Dr Patek hopes that future research may identify other creatures using the same principles, she also recognises the unusual quality of the spiny lobsters sound. She comments:
‘If it turns out that only the spiny lobsters produce sound with this mechanism, then I suppose it is a remarkable twist of evolutionary history that such a unique method of sound production arose in just one group of organisms.’
Meanwhile Dr Patek is due to move on to new areas of research as she embarks on a three-year postdoctoral fellowship, where she plans to study the evolution and communication of the mantis shrimp.
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| Not All Lobsters Are Noisy |
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Not all lobsters are tuneful. The spiny lobster belongs to the Palinuridae family but differs from the lobsters that we usually see in restaurant tanks.
The spiny lobster can grow up to 16 inches long. It has a distinct blotchy pattern and instead of claws they have a pair of long, stiff antennae.
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| Museum Modifications |
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The unusual nature of the creature’s sound has recently led The Science Museum in London to modify its Antenna exhibition.
The exhibition changes regularly to reflect new developments in science and technology and has now been adapted to make room for moulted lobster shells. |
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