Magnetic sense and direction recognition of a non-migratory fishes.

磁敏感性研究与动物的定向和导航有关。虽然在许多动物体内都发现了磁铁矿，但关于磁铁矿在迁徙动物定位和导航中的作用的研究并不总是成功的。本研究考察了非洄游鱼类的磁敏感性和利用地磁线索定位的能力。结果表明：1)采用条件反射法和心电图法检测磁感应灵敏度，是一种灵敏、实用的方法。2)用该方法测定了鳗鱼以及泥斗鱼、罗非鱼、黑带岩鱼等非洄游鱼类的磁敏感性。磁敏感性似乎在这些非洄游鱼类的局部归巢中发挥了作用。3)测定了海鳗、河鳗和养殖鳗鱼的磁敏感性。本研究的结果与过去的研究结果进行了比较，这些研究表明美洲鳗、摩尔鳗和欧洲鳗没有磁感。4)采用条件反射法和心电图法检测了嗅觉缺失的日本鳗鲡的磁敏感性。将煮沸凡士林（130 ~ 140℃）注入鳗鱼鼻腔，使其丧失嗅觉。凡士林是研究鳗鱼嗅觉及嗅觉相关行为的常用方法。没有嗅觉的鳗鱼对磁场没有反应，可能是由于果冻注射对嗅觉器官的损害。5)采用条件反射法和心电图法检测玻璃鳗期（新变态幼鳗）日本鳗鲡的磁敏感性。经过10-40次条件反射后，所有的玻璃鳗都表现出明显的条件反射。结果表明，玻璃鳗具有较高的磁敏感性，可能在生命早期就获得了地磁信息。据推测，在玻璃鳗鱼阶段，当从开阔的海洋向大陆架和沿海水域迁移时，通过逆转地磁方向，银相成年鳗鱼找到了回到海洋产卵地的路。少

Magnet sensitivity studies have been related to orientation and navigation of animals. While the magnetite has been found in variety of animals, studies on the involvement of the magnetite in orientation and navigation of migratory animals are not always successful. This study examined the magnetosensitivity and ability of non-migratory fishes to orient by means of geomagnetic cues. The results obtained are as follows :1)Conditioning and electrocardiography method was employed to examine the magnetosensitiviy and found to be highly sensitive and useful method.2)With this method, magnetosensitivity was determined for eel as well as non-migratory fishes such as mud hopper, tilapia and darkbanded rockfish. Magnetosensitivity seems to be used in the local homing in these non-migratory fishes.3)Magnetosensitivity was determined for marine eels, river eels and farmed eels. Results of the present study were compared with those of past studies which showed no magnetic sense in the American eel … More and the European eel.4)Magnetosensitivity in anosmic Japanese eel was examined by conditioning and electrocardiography. Five eels from a freshwater farm were made anosmic by injection of boiling petroleum jelly (130-140℃) into the nasal cavity, a technique widely used in studies on olfaction and olfaction-related behavior of eels. The anosmic eels did not respond to the magnetic field, presumably due to damage of the olfactory organ from the jelly injection.5)Magnetosensitivity of the Japanese eel at the glass eel phase (newly metamorphosed juveniles) was examined by conditioning and electrocardiography. After 10-40 conditioning runs, all the glass eels exhibited a significant conditioned response. The results indicate that glass eels have high magnetosensitivity and probably acquire geomagnetic information that early in life. It is hypothesized that silver-phase adult eels find their way back to the oceanic spawning ground by reversing the geomagnetic direction that had been detected and ‘memorized' during the glass eel phase when migrating from the open ocean towards the continental shelf and coastal waters. Less