It is not yet understood how turtles detect magnetism, nor exactly how they derive a navigational map from it.

人们对海龟如何探测磁场还不理解，对于它们怎样从磁场获得导航图也不能做出正确解释。

According to Michael Greenfield, a director with NSF's Animal Behavior Program, "Older turtles would need a more accurate map, as they must do more than simply Orient seaward and enter a current."

据国家基金会动物行为项目主任迈克尔·格林菲尔德说：“较年长的海龟将需要更加精确的地图，因为它们并不仅仅是瞄准大海走进入水流。”

Now it seems the scientists underestimated the turtles' abilities, with research showing they use Earth's magnetic field to create a mental map that covers all four points of the compass.

现在看来，科学家似乎低估了海龟的能力。研究表明海龟利用地球磁场为自己确定的地图可涵盖东西南北四个方位。