英語聽力文摘 米諾魚的自殺式生存策略

For Minnows, A Suicidal Survival Strategy

北美多種小型魚類，特別是鯉科(Cyprinidae)魚類的總稱。亦指蔭魚科(Umbridae)和鱂科(Cyprinodontidae)魚類，minnow一詞又泛指許多大型魚類的幼魚。北美的鯉科米諾魚包括多種小型淡水魚，如名為閃光魚的美鯿屬(Notemigonus)和閃鱥屬(Notropis)魚類以及名為鈍吻米諾魚及肥頭米諾魚的呆魚屬(Pimephales)魚類。許多為盛產(chǎn)種類，一些是有價值的活釣餌，并有時進行人工養(yǎng)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 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 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 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.

譯文：

在池塘或溪流的下面是一個魚吃魚的世界。小米諾魚通常都是大魚(例如梭子魚)的午餐。也許你認為美味的小米諾魚應(yīng)該藏起來，不被發(fā)覺才對，然而事情并非總是如此。如果一條小米諾魚被一條梭子魚攻擊劃破了皮，它就會釋放出一種化學(xué)物質(zhì)吸引來更多的梭子魚。為什么一只已經(jīng)被攻擊的小米諾魚想要引來更多的麻煩呢?難道那些受傷的小米諾魚們有某個瘋狂的想死的念頭嗎?

這個看似自殺性的行為實際上卻是一個聰明的生存策略。小米諾魚釋放的化學(xué)物質(zhì)有兩大顯著的功能。首先，它能警告其他小米諾魚這里有危險。通常小米諾魚和自己的近親們成群的游動，于是這種化學(xué)警鐘就可以警告其他米諾魚遠離那些潛在的危險水域。即使原先的小米諾魚被吃了，它的兄弟姐妹們也可以活下來繁殖后代。從遺傳學(xué)的角度來看，這種自殺式犧牲是可行的。

也許你會好奇這個化學(xué)物質(zhì)的另一大功能——吸引更多的梭子魚。小米諾魚被相對較小的梭子魚襲擊時更容易被劃傷皮膚，而大個兒的梭子魚則會將米諾魚們一口吞下。正因為如此，這種警報物質(zhì)通常在被小型梭子魚襲擊的時才會釋放出來的。也就是說，這種化學(xué)物質(zhì)將會引來比眼前攻擊者還要大的梭子魚。梭子魚對于吃自己的同類完全毫無顧忌，所以如果一條大梭子魚看到一條小梭子魚正在捕食一條小米諾魚，大梭子魚則會追趕小梭子魚一飽口福，而讓小米諾魚獲得一線生機。

這一切很像《侏羅紀公園》的結(jié)局。人類眼看著就要被可怕的暴龍們吃掉，正在這時，他們激烈的爭斗聲召喚出了更大的捕食者：雷克斯霸王龍。雷克斯霸王龍吃掉了多倫多暴龍，而讓人類逃出生天。