Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA.
Curr Biol. 2011 Mar 22;21(6):463-6. doi: 10.1016/j.cub.2011.01.057. Epub 2011 Feb 25.
Long-distance animal migrants often navigate in ways that imply an awareness of both latitude and longitude. Although several species are known to use magnetic cues as a surrogate for latitude, it is not known how any animal perceives longitude. Magnetic parameters appear to be unpromising as longitudinal markers because they typically vary more in a north-south rather than an east-west direction. Here we report, however, that hatchling loggerhead sea turtles (Caretta caretta) from Florida, USA, when exposed to magnetic fields that exist at two locations with the same latitude but on opposite sides of the Atlantic Ocean, responded by swimming in different directions that would, in each case, help them advance along their circular migratory route. The results demonstrate for the first time that longitude can be encoded into the magnetic positioning system of a migratory animal. Because turtles also assess north-south position magnetically, the findings imply that loggerheads have a navigational system that exploits the Earth's magnetic field as a kind of bicoordinate magnetic map from which both longitudinal and latitudinal information can be extracted.
长距离动物迁徙者通常以暗示其对纬度和经度都有感知的方式进行导航。虽然已知有几种物种使用磁场线索作为纬度的替代品，但尚不清楚任何动物如何感知经度。由于磁性参数通常在南北方向上变化较大，而不是在东西方向上变化较大，因此它们似乎不太适合作为纵向标记。然而，我们在这里报告说，来自美国佛罗里达州的孵化棱皮龟（Caretta caretta）在暴露于存在于两个具有相同纬度但位于大西洋两岸的磁场中时，会以不同的方向游泳，这有助于它们沿着其圆形迁徙路线前进。结果首次证明，经度可以被编码到迁徙动物的磁性定位系统中。由于海龟也通过磁场来评估南北位置，因此这些发现意味着棱皮龟具有一种导航系统，它利用地球磁场作为一种双坐标磁场地图，从中可以提取经度和纬度信息。
