Optic flow odometry operates independently of stride integration in carried ants
Sarah E. Pfeffer, Matthias Wittlinger
觅食的沙蚁会穿越撒哈拉沙漠灼热的沙子寻找死去的蜘蛛和其他节肢动物，从而为整个蚁群提供食物。当地条件是如此恶劣，以至于蚂蚁在往返于巢穴时不得不成为高效的导航者，从而避免被烤焦。
此前研究证实，这些昆虫会记下它们的步数，以测量自己走了多远。一项日前在线发表于《Science》杂志的研究则表明，它们还能仅靠视觉找到回家的路。沙蚁利用的是“光流”—— 一种类似于人们乘坐汽车时透过窗口估测距离和方向的方法。
为弄清真相，研究人员用亮黄色颜料“蒙住”蚂蚁的眼睛，以观察它们能否找到返回巢穴的路。无论是否被“蒙住”眼睛，行走至距巢穴一定距离的有经验的觅食者都能顺利返回，因为它们会记下到达该地点需要的步数。不过，只有被觅食蚂蚁携带至卫星巢穴时才会冒险出去的巢内工蚁，在被携带行走了与其觅食同伴一样的距离后，只能在不被“蒙住”眼睛的情况下才能返回巢穴。
尽管巢穴工蚁并不知道身处的地方离家有多少步，但它们能依靠视觉返回。这着实令人惊讶，因为视觉仅被认为在导航中发挥了辅助作用。
研究人员认为，这些蚂蚁在撒哈拉沙漠的栖息地是如此的危险，以至于它们进化出两种不同的机制——计步和光流——应对恶劣的环境。
来源：中国科学报 徐徐
Abstract
Cataglyphis desert ants are impressive navigators. When the foragers roam the desert, they employ path integration. For these ants, distance estimation is one key challenge. Distance information was thought to be provided by optic flow (OF)—that is, image motion experienced during travel—but this idea was abandoned when stride integration was discovered as an odometer mechanism in ants. We show that ants transported by nest mates are capable of measuring travel distance exclusively by the use of OF cues. Furthermore, we demonstrate that the information gained from the optic flowmeter cannot be transferred to the stride integrator. Our results suggest a dual information channel that allows the ants to measure distances by strides and OF cues, although both systems operate independently and in a redundant manner.
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