Lobsters moult every year, leaving behind their entire shell, including their eye and tentacle covers. The new shell takes two weeks to harden, leaving the soft lobster vulnerable to predators. The creature has areas of soft tisue at the base of each antenna covering a plectrum, which is used to create a rasping sound when threatened by predators. A rubbing motion creates frictional interactions similar to a violin bow drawn acros a string. The carapace (upper shell) of a lobster from the London Aquarium, displayed at the Science Museum, London, 2001.
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