Mechanisms of Orientation and Navigation

定位与导航的机制海龟刚从海底海滩的地下巢穴中出来，就开始了惊人的长距离迁徙。它们爬向大海，穿过海浪，然后迅速确定航向，向开阔的海洋游去，在游到看不见陆地后保持方向。对于小海龟是如何在没有明显标志的广阔海洋中保持航线的，人们知之甚少。在海滩附近，波浪方向提供了一个可靠的线索，这是幼仔最初使用的线索。但在远离陆地的地方，波浪不再可靠地指示方向，这些幼仔似乎依赖于地球的磁场。最近的实验表明，海龟有一个发达的磁罗盘，使他们保持一个特定的方向，即使在完全黑暗。对于像海龟这样的长途迁徙者来说，地磁场不仅为指南针的方位提供了可能的线索，而且是全球定位信息的潜在来源。地球磁场的几个参数可预测地随纬度变化，似乎孵化的海龟可以感知这些参数。Lohmann博士将进行的研究旨在调查：(1)幼龟如何使用这些地磁参数进行全球定位；(2)幼海龟如何获得方向性偏好以及方向性偏好如何影响取向；(3)幼崽用来探测波浪方向的机制，以及这些信息如何与磁罗盘的信息相互作用。所有种类的海龟现在都受到威胁或濒临灭绝。因此，这项研究将为试图拯救这些动物免于灭绝的保护工作者提供有用的信息。此外，它还将提供有关动物（包括海龟、鱼类和鲸鱼）如何利用地球磁场信息进行导航的宝贵信息。

NONTECHNICAL SUMMARY Lohmann, K., IBN 94-19993 Mechanisms of Orientation and Navigation Sea turtle hatchlings begin an amazing long-distance migration as soon as they emerge from their underground nests on oceanic beaches. They scramble to the sea and swim through the surf, then quickly establish a course towards the open ocean, Maintaining their direction after swimming beyond sight of land.. Little is known about how hatchling sea turtles maintain their course through a vast ocean that contains no obvious landmarks. Near the beach, wave direction provides a reliable cue, Which the hatchlings seem to use initially. But farther from land, where waves no longer reliably indicate direction, the hatchlings appear to depend on the magnetic field of the earth. Recent experiments have demonstrated that sea turtles have a well- developed magnetic compass that allows them to maintain a specific heading, even in total darkness. For long-distance migrants such as sea turtles, the geomagnetic field not only provides a possible cue for compass orientation, but a potential source for worldwide positional information. Several parameters of the earth s magnetic field vary predictably with latitude and it appears that hatchling sea turtles can sense these parameters. The research that Dr. Lohmann will carry out is designed to investigate: (1) how hatchlings may use these geomagnetic parameters in global position finding; (2) how young sea turtles may acquire a directional preference and how the preference influences orientation; and (3) the mechanism hatchlings use to detect wave direction and how this information interacts with the information from the magnetic compass. All species of sea turtles are now either threatened or endangered. Thus this research will provide information useful to conservation workers trying to save these animals from extinction. In addition it will provide valuable information about how animals (including turtles, fis h and whales) navigate using information from the magnetic field of the earth. .