Downstream trout swim but can't hide.Little shrimplike creatures called amphipods can detect danger ahead even when that predator--a hungry trout--is lurking See lurk. (messaging, jargon) lurking - The activity of one of the "silent majority" in a electronic forum such as Usenet; posting occasionally or not at all but reading the group's postings regularly. downstream. "In running waters, chemical cues have generally been assumed to always come from upstream locations," reports an article by Jonas Dahl and his colleagues of Lund University Lund University has 7 faculties, with additional campuses in the cities of Malmö and Helsingborg, with a total of over 42,500 people studying in 50 different programmes and 800 separate courses. in Sweden. Yet, observations in the wild and in laboratory tests show that the amphipods somehow pick up cues of downstream hazards. Given a choice of two paths in an artificial stream, the amphipod Gammarus pulex Gammarus pulex, sometimes called "freshwater shrimp" in error, is a freshwater amphipod. The adult Gammarus pulex is typically around 11 mm long (though males can be up to 20 mm), with a curved, brown-yellow body. avoided drifting along with water flowing toward predatory brown trout brown trout Prized and wary European game fish (Salmo trutta, family Salmonidae) that is favoured for food. The species includes several varieties (e.g., the Loch Leven trout of Britain). The brown trout is recognized by the light-ringed black spots on its brown body. . The little crustaceans also avoided water where researchers had dropped trout scents downstream but did not respond to visual cues--trout in glass tubes. The amphipods' secret may be to check for trout chemical signs in backflows, little stray currents that do not follow the main flow of a stream. The amphipods' skill at detecting danger could change models of predator effects in running water, say the authors, whose analysis appears in the July 22 Proceedings Of The Royal Society Proceedings of the Royal Society is a scientific journal published by the Royal Society of London. Today, the Royal Society publishes two proceeding series:
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