英语听力文摘 English Digest 279、米诺鱼的自杀式生存策略

　　For Minnows, A Suicidal Survival Strategy

北美多种小型鱼类，特别是鲤科(Cyprinidae)鱼类的总称。亦指荫鱼科(Umbridae)和鱂科(Cyprinodontidae)鱼类，minnow一词又泛指许多大型鱼类的幼鱼。北美的鲤科米诺鱼包括多种小型淡水鱼，如名为闪光鱼的美鯿属(Notemigonus)和闪鱥属(Notropis)鱼类以及名为钝吻米诺鱼及肥头米诺鱼的呆鱼属(Pimephales)鱼类。许多为盛产种类，一些是有价值的活钓饵，并有时进行人工养殖以供利用。

Beneath the surface of a pond or stream it’s a fish-eat-fish world, and the tiny minnow is often lunch for larger fish such as pike.  You’d think a tasty minnow would try to remain inconspicuous, but this isn’t always the case.  If a minnow’s skin is damaged by an attacking pike, it releases a chemical that attracts more pike.  Why would a minnow that’s already being attacked want to attract more trouble?  Do injured minnows have some kind of crazy death wish?

　　This seemingly suicidal behavior is actually a clever survival strategy.  The minnow’s chemical has two distinct functions.  First, it warns other minnows about the danger.  Minnows travel in schools with close relatives, so this chemical alarm warns the others away from potentially dangerous waters.  Even if the original minnow is eaten, its brothers and sisters will live to reproduce.  From a genetic 1 standpoint, this self sacrifice makes sense.

You might wonder about the chemical’s other function though–to attract more pike.  A minnow’s skin is most likely to be damaged in an attack from a relatively 2 small pike.  Larger pike simply swallow their minnows whole.  Because of this, the alarm substance is usually released when a small pike is attacking.  This means that the chemical might well attract pike that are larger than the minnow’s current assailant.  Pike have no qualms 3 about eating other pike, so if a big one sees a smaller pike chasing a tiny minnow, that big pike will go after the larger mouthful, allowing the minnow to escape.

It’s much like the end of Jurassic Park.  The humans were about to be eaten by evil velociraptors, when the noise of their struggle summoned a bigger predator:  Tyrannosaurus Rex.  T-rex ate the raptors, allowing the humans to escape.

译文：

在池塘或溪流的下面是一个鱼吃鱼的世界。小米诺鱼通常都是大鱼（例如梭子鱼）的午餐。也许你认为美味的小米诺鱼应该藏起来，不被发觉才对，然而事情并非总是如此。如果一条小米诺鱼被一条梭子鱼攻击划破了皮，它就会释放出一种化学物质吸引来更多的梭子鱼。为什么一只已经被攻击的小米诺鱼想要引来更多的麻烦呢？难道那些受伤的小米诺鱼们有某个疯狂的想死的念头吗？

这个看似自杀性的行为实际上却是一个聪明的生存策略。小米诺鱼释放的化学物质有两大显著的功能。首先，它能警告其他小米诺鱼这里有危险。通常小米诺鱼和自己的近亲们成群的游动，于是这种化学警钟就可以警告其他米诺鱼远离那些潜在的危险水域。即使原先的小米诺鱼被吃了，它的兄弟姐妹们也可以活下来繁殖后代。从遗传学的角度来看，这种自杀式牺牲是可行的。

也许你会好奇这个化学物质的另一大功能——吸引更多的梭子鱼。小米诺鱼被相对较小的梭子鱼袭击时更容易被划伤皮肤，而大个儿的梭子鱼则会将米诺鱼们一口吞下。正因为如此，这种警报物质通常在被小型梭子鱼袭击的时才会释放出来的。也就是说，这种化学物质将会引来比眼前攻击者还要大的梭子鱼。梭子鱼对于吃自己的同类完全毫无顾忌，所以如果一条大梭子鱼看到一条小梭子鱼正在捕食一条小米诺鱼，大梭子鱼则会追赶小梭子鱼一饱口福，而让小米诺鱼获得一线生机。

这一切很像《侏罗纪公园》的结局。人类眼看着就要被可怕的暴龙们吃掉，正在这时，他们激烈的争斗声召唤出了更大的捕食者：雷克斯霸王龙。雷克斯霸王龙吃掉了多伦多暴龙，而让人类逃出生天。