动物行为学(通识)-国立台南大学.PPT

Ayo 教材 (動物行為學 2011 通識) * Sea turtles migrate with extraordinary precision The earth’s magnetic field provides a global positioning system that tells them their position relative to a goal Juveniles and adults use the geomagnetic field as navigational map A more complex use than hatchlings The magnetic field tells the turtle whether it is north or south of its goal It moves in the appropriate direction until it encounters other cues that identify the feeding grounds Ayo 教材 (動物行為學 2011 通識) * As sea turtles mature, they use the earth’s magnetic field to determine their location relative to home. Sea turtles return to the same feeding grounds every year. The turtle swam in a direction that would return them to their feeding grounds (the test site) if they actually had been displaced. Ayo 教材 (動物行為學 2011 通識) * Magnetite (磁鐵礦) Magnetite: a magnetic mineral in animals It orients to the geomagnetic field Found in bees, trout, salmon, birds, and sea turtles In vertebrates, these deposits are found in the head or skull It can twist to align with the earth’s magnetic field, stimulating a stretch receptor In the rainbow trout, nerves contain fibers that respond to magnetic fields Along with their light-dependent inclination compass, birds have magnetite deposits in their upper beak The polarity compass of bats is based on magnetite Ayo 教材 (動物行為學 2011 通識) * Juvenile vs. adult silvereye receptor systems Adult, not juvenile, migrants have a navigational map Juvenile silvereyes remained oriented in the appropriate migratory direction after a magnetic pulse They have not yet formed a magnetic map Their orientation is based on an innate migratory program They use their magnetic compass, based on the light-dependent magnetoreception process, to head in the appropriate direction Ayo 教材 (動物行為學 2011 通識) * Chemical cues Some species use olfactory cues for orientation during homing Olfaction and salmon homing Salmon hatch in the cold, clear fresh water of rivers or lakes and then sw