động vật hoang dã BBC Magazine là điều cần thiết đọc cho bất cứ ai có một niềm đam mê cho động vật hoang dã, những người muốn hiểu Tốt nhất tạp chí của Anh Tạp chí động vật hoang dã BBC động vật hoang dã là một kỷ niệm của thế giới tự nhiên, tính năng tất cả các khám phá mới nhất | DAVID BRIAN BUTVILL ZOOLOGIST Our Discoveries sleuth David writes about science and nature for magazines radio and tv. He lives in Costa Rica where he eagerly assists his marine-biologist wife in the field. DISCOVERIES Supersensitive seal stubble Biologists discover a hidden talent of seal whiskers. The whiskers of a harbour seal Phoca vitu-lina may look cute but they are also deadly hunting tools - like radar they help the seal to locate fish that are nowhere in sight according to a new study. A seal s facial hair can detect the wake that a fish leaves behind as it swims. To assess just how fresh trails have to be for a seal to take notice a team led by Wolf Hanke from the University of Rostock in Germany tested a six-year-old male named Henry at a local zoo. The team built an underwater enclosure in Henry s pool. Through a slit in the top they inserted a rudder-like paddle shaped like a fish tail and moved it either from left to right or right to left. After a short delay Henry who was blindfolded was allowed to access the enclosure. He indicated the direction the fish had gone by nuzzling that side of the box each correct answer was rewarded with a piece of herring. Naturally the longer Henry had to wait before entering the more difficult he had discerning the SOURCE J. Exp. Biology vol213 pp2194-200 LINK http id 158 correct direction. Still he almost always got it right when he arrived within IO seconds of the prey passing by. Even after 35 seconds - an eternity for a fleeing fish - he made the right choice more than 70 per cent of the time. So a harbour seal on the hunt can track fish starting from a spot they d fled half a minute earlier or more - see box . It doesn t need to be near prey to know in which direction to look for them. To see exactly what seals home in on the researchers used imaging techniques to examine the flow of water created during the study. A swimming fish creates a series of vortices that spin dockwise off its
