Sometimes it pays to look like a pile of poop. At least if you’re a tasty caterpillar trying to avoid getting eaten by hungry birds. Because a study in the journal Science shows that even young chicks tend to overlook caterpillars disguised as dung.
如果你是一条肥嫩多汁的毛毛虫，把自己模拟成一根树枝很可能就能鸟嘴余生。《科学》杂志刊载的一项动物实验表明，生物拟态的效果立竿见影，只见过树枝一面的初生雏鸡就险些被拟态成树枝的毛毛虫骗过。
Animals have come up with some pretty clever tricks for keeping themselves off a predator’s dinner plate. Some use camouflage, adopting colors and patterns that help them blend into the environment. Others masquerade as something inedible, like bird droppings or twigs. But scientists got to wondering whether the two approaches are really so different. Maybe critters dressed as twigs also blend in so that predators just don’t see them. To find out, scientists presented some twiggy-looking caterpillars to two sets of hand-reared chicks. They found that baby birds that had never seen sticks before gobbled those bad boys right up. But chicks who were shown real twigs first took much longer to peck at the mimics, and did so more gingerly than their naïve friends.
为免做天敌盘中餐，很多生物都掌握着高明的防身术。其中一些利用自身的颜色和体形进行伪装，融入周围的自然环境，让天敌不易察觉；另一些则将自身模拟成诸如鸟粪、枯枝这类无法食用的事物，称之为拟态。科学家们想知道的是，伪装和拟态之间是否真的那么泾渭分明，因为假若有昆虫拟态成枯枝，不也是融入了环境，让其天敌视而不见吗？为了搞清楚，科学家们进行了一次实验，他们将一些长相酷似树枝的毛毛虫摆到两组人工养殖的鸡崽面前。一组鸡崽儿压根没见过什么是树枝，不容分说便把毛毛虫吞下肚；另一组鸡崽儿则见识过科学家们展示给它们看的树枝，当它们看到这些长得像树枝的毛毛虫就踯躅起来，试探了好一会儿才小心翼翼地享用了毛毛虫大餐。
That means the birds could see the caterpillars, but were fooled by the costume, at least temporarily. Which, for a caterpillar on a leaf in the wild, could mean the difference between eating and being eaten.
这项实验结果表明，后一组鸡崽儿虽然能看到那些毛毛虫，却被毛毛虫的长相给迷惑了，至少是被迷惑了一阵儿。而这一阵儿，对那些趴在野外树叶上的毛毛虫，可是生死一线。