【英语时差8,16】螳螂的眼睛（下）（在线收听）

There are many dung beetles competing for a limited amount of food at a dung pile, so when an individual is finished rolling a ball of dung it is in its best interest to make a quick escape. The fastest way to travel is in a straight path. Scientists noticed that when the moon was visible, these dung beetles did just that; they traveled in straight paths. But when it was a cloudy night, the beetles’ paths became shaky and erratic. To be sure the beetles were indeed using the moon’s polarization and not the moon itself, the researchers used a filter that changed the pattern of the polarized moonlight by 90 degrees. The beetles responded by changing their course by 90 degrees. Scientists suspect that the dung beetle isn’t the only animal to navigate by the moon’s polarization and that more such creatures will soon be discovered.