雅思听力真题练习：蜜蜂的交流

　　雅思听力真题练习：蜜蜂的交流

　　A paper published in Nature on May 12th (1) provides new data that resolvesa long-standing scientific controversy. In the 1960s, Nobel Prize winningzoologist, Karl von Frisch, proposed that honeybees use dance (the“waggledance”) as a coded message to guide other bees to new food sources. However,some scientists did not accept von Frisch’s theory. Using harmonic radar,scientists, funded in part by the UK’s Biotechnology and Biological SciencesResearch Council have now tracked the flight of bees that had attended a “waggledance” and found that they flew straight to the vicinity of the feeding site, aspredicted by von Frisch. The tracks allowed the scientists to determine howaccurately bees translate the dance code into successful navigation, and showedthat they correct for wind drift even when en route to destinations they havenever visited before.

　　If a honeybee worker discovers a good feeding site it is believed that sheinforms her nest mates through a dance that describes the distance and directionof the feeding site. This ‘dance language’ was first described by Karl vonFrisch in the 1960s but his experiments also showed that bees that had attendedthe dance (recruits) took far longer to get to food than would be expected. Thistime delay caused other scientists to argue that the recruits did not read theabstract code in the dance at all, but found the food source simply by trackingdown the smell that they had picked up from the dancing bee. Another suggestionwas that recruits simply followed the dancer when she flew back to the food, andthen other bees joined in. The controversy has persisted because prior to theadvent of harmonic radar, no one could show exactly where the recruits flew whenthey left their hives.

　　The scientists watched the waggle dance occurring in a glass observationhive and identified recruits. They captured these recruits as they left thehive, attached a radar transponder to them and then tracked their flight pathsusing harmonic radar. Most recruited bees undertook a flight path that took themstraight to the vicinity of the feeding site where they all spent a lot of timein searching flights, trying to locate its exact position. This searchingbehaviour accounts for the time lag that caused the original controversy.

　　In another set of experiments, bee recruits leaving the hive were taken torelease sites up to 250m away. These bees flew, not to the feeding site, but inthe direction that would have taken them to the feeding site had they not beendisplaced from the hive. This result adds weight to von Frisch’s original theoryand allows alternative hypotheses about bee behaviour to be firmlydiscounted.

　　Entomologists have long known that bees use polarized sunlight to navigate.Two Swiss scientists now say that a bee's navigational "map" lies embedded inspecial photoreceptors in its eyes. According to Samuel Rossel and RudigerWehner of the University of Zurich, "... the array of receptors [in the bee'seyes] forms a template which the bee uses to scan and match the polarizationpatterns in the sky."

　　In the 1940s, Nobel laureate Karl von Frisch showed that bees have a simpleyet elegant way of communicating the location of distant sources of food. When aforaging bee returns to the hive, she performs a "waggle dance" consisting of ashort run ending in a loop that returns her to the beginning point of her run.The direction of her run indicates the direction of the food source with respectto the sun.

　　A sister bee observing this performance somehow remembers the size of theangle between the sun and the food indicated by the dancing bee. She flies outof the hive, makes a quick calculation of the position of the sun, and zips awayat the same angle.

　　Bees have compound eyes made of almost 6,000 tiny lenses covering theopenings of equally tiny tubes. Each tube contains eight light receptors thatlook like toothbrushes with the bristles facing each other at the lens end ofthe tube; the "handle" is the nerve going to the brane. The tubes located at thetop of the bee's eye contain "toothbrushes" that specialize in detectingpolarized ultraviolet light. Beginning at the back of the bee's compound eye andcontinuing around to the front, these specialized photoreceptors in each tubeare arranged in a pattern that matches the direction of polarizedsunlight....