How spiny lobsters make scary noises.On an evolutionary tree, spiny lobsters sit near crickets. Yet musically, the crustaceans belong closer to a person torturing a violin. Crickets make the sound track for summer by rubbing a hardened scraper See scraping. , against a patch of ridges. One of the insect's forewings carries the scraper and the other has the ridges. In the May 10 NATURE, Sheila N. Patek of Duke University in Durham, N.C., reports that spiny lobsters rely on an entirely different mechanism to generate their raspy rasp·y adj. rasp·i·er, rasp·i·est Rough; grating. Adj. 1. raspy - unpleasantly harsh or grating in sound; "a gravelly voice" grating, rasping, gravelly, scratchy, rough racket. People grappling with spiny lobsters above and under water have gotten an earful ear·ful n. 1. An abundant or excessive amount of something heard, such as talk or music. 2. Gossip, especially of an intimate or scandalous nature. 3. A scolding or reprimand. of the creatures' harsh rasping sounds. "It's very abrasive," Patek says. (Visit www.sciencenews.org for a sound sample.) Rather than being hard like most of the animal's carapace carapace (kâr`əpās), shield, or shell covering, found over all or part of the anterior dorsal portion of an animal. In lobsters, shrimps, crayfish, and crabs, the carapace is the part of the exoskeleton that covers the head and thorax , a lobster's scraper or plectrum--a pink protrusion protrusion /pro·tru·sion/ (-troo´zhun) 1. extension beyond the usual limits, or above a plane surface. 2. the state of being thrust forward or laterally, as in masticatory movements of the mandible. at the base of each antenna--has a more leather like texture. Observers have seen spiny lobsters scrape their leathery plectra across scaly ridges below their eyes. At first, Patek assumed that even this soft scraper could rasp the way crickets do with their harder one. After using underwater microphones and high-speed videos to catch the Caribbean spiny lobster (Panulirus argus) in the act of making noise, Patek recalls saying to herself, "Wait a minute! That's not what's going on What's Going On is a record by American soul singer Marvin Gaye. Released on May 21, 1971 (see 1971 in music), What's Going On reflected the beginning of a new trend in soul music. ." She could see that a lobster plectrum moves jerkily and that sound comes only when the plectrum slides, not when it sticks. If the lobsters were depending on a cricketlike washboard mechanism, the sound would coincide with the plectrum's impact with a ridge peak. Patek concludes that the lobsters make their noises by drawing their plectra in a stick-slip movement across the ridges. It's much like a violin bow pulling across a string, she says. This stick-slip mechanism is also behind the tooth-tingling sounds of a finger squeaking over the surface of a balloon, she explains. The process enables a lobster to scratch out alarms and protests even at molting molting, periodical shedding and renewal of the outer skin, exoskeleton, fur, or feathers of an animal. In most animals the process is triggered by secretions of the thyroid and pituitary glands. time, when its body is soft and most vulnerable. The clawed lobsters of culinary import make noise, too, Patek points out, but they rely on a swiftly vibrating muscle in their heads. |
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