The bigeyes are the equivalent of bats - night feeders that leave the cave each evening. And like all cave commuters they are most vulnerable at the scheduled time of departure. A bottleneck funnels these exiting bats into dense concentrations attracting the attention of others. The bats can detect the snakes using echolocation, but the snakes are literally in the dark. They can see nothing. The strikes seem to be largely hit-and-miss, but the snakes have a secret weapon. They can actually sense each bat flying past. Receptors in the snake's head pick up the heat given off by the flying bats, as this thermal image shows. 这些“大眼鲷”和蝙蝠一样是昼伏夜出的动物。而且和所有进出岩洞的居民一样,它们既定的出洞时间是最危险的时候。狭小的洞口中挤着这么多的出行者吸引了其他动物的注意。蝙蝠可以用回声定位器探测到蛇的位置,但蛇几乎是在黑暗中——它们什么也看不见。蛇的攻击似乎无法命中目标,但蛇有一个秘密武器。他们可以感觉到每一只飞过的蝙蝠。它们头上的感觉器官可以感觉到飞过的蝙蝠身体发出的热量。