If you ___1___ in the Atlantic, you'd flounder on which way to swim. But a hatchling loggerhead turtle would know just where to paddle—by reading the Earth's magnetic field. Scientists knew turtles can ___2___ latitude this way. Because the field varies a lot from north to south. But not east to west. So how do turtles know which side of the Atlantic they're on?
To find out, researchers strapped hatchlings into custom Lycra bathing suits, ___3___ to a tracking unit. They plopped each turtle into a small pool surrounded by magnetic coils. And they ___4___ the magnetic fields of Puerto Rico and the Cape Verde Islands, two points along the turtles' migration, with equal latitudes but different longitudes. The hatchlings swam opposite directions in the two trials—both being the right ones, to stay on the migratory track. The study appears in the journal Current Biology. [Nathan Putman et al., "Longitude Perception and Bicoordinate Magnetic Maps in Sea Turtles"]
The researchers say turtles may calibrate their migratory maps by sensing the magnetic field's intensity, and its inclination to the Earth's surface—a combo that gives each point of the migration a unique signature. As for any human navigators out there, you'll just have to ___5___ for a GPS.
【視聽版科學小組榮譽出品】
splashed down pinpoint tethered replicated shell out
假如你一不小心從半空中撲通一聲掉進浩瀚大西洋，估計該找不著北了吧。不過幼蠵龜能通過地球磁場來判斷該往哪里走?？茖W家們已經(jīng)發(fā)現(xiàn)海龜能夠通過地球磁場判斷其所在地的精確緯度，因為地球磁場南北方向差異較大，而東西方向則不然。那海龜是如何知道它們身在大西洋的何處的呢？ 為此，科學家們給小海龜穿上定制的萊卡泳衣以進行追蹤，然后將每一頭小海龜安置在一個放有線圈的小游泳池中，并利用這些線圈模擬出波多黎各和佛得角群島附近的磁場，它們所在的緯度相同但經(jīng)度不同，是小海龜遷徙必經(jīng)的兩個地方。科學家們發(fā)現(xiàn)小海龜在不同的磁場中游向相反方向，但都是在遷徙路線上游動，方向判斷得相當正確。該研究成果刊登在《當代生物學》雜志上。 科學家們認為海龜是通過感應周圍磁場密度以及它們和地球表面的傾角來判斷遷徙方向的——這真是標記路標的完美組合啊~要說那千千萬萬的海員在茫茫大海中該如何是好？買個GPS就OK~