【经济学人】蜘蛛恐惧症丨2017.03.16丨总第845期

ARACHNOPHOBIA is a common and powerful fear. Spiders sit high in the pantheon of species that have an outsized terror-to-danger ratio. But, unsettling though they may be, the eight-legged do excel at keeping six-limbed pests in check. They prey upon insects in vast quantities, while, for the most part, leaving people alone. Indeed, in 1957 William Bristowe, a British arachnologist, wondered whether British spiders might kill prey equivalent in mass to all of the people then living in Britain.

蜘蛛恐惧症是一种常见且强烈的恐惧感，在有巨大的恐怖危险概率的物种排名中，蜘蛛的排名靠前。但是，尽管它们可能会令人不安，八条腿的蜘蛛在控制六足害虫上却做得很好。它们大量捕捉昆虫，不过，大多数情况下它们远离人类。在1957年，英国的节肢动物学家William Bristowe对一个问题很好奇，即英国蜘蛛捕杀的猎物数量与当时居住在英国的民众捕食的猎物数量是否相同。

• arachnophobia蜘蛛恐惧症

In research published this week in the Science of Nature, Martin Nyffeler of the University of Basel, in Switzerland, and Klaus Birkhofer of Lund University, in Sweden, attempt to put some numbers on spiders’ dining habits. Starting with the available data on the mass of spiders found per square metre in Earth’s main habitat types—forests, grasslands, fields of crops and so on, they calculated the amount of prey required in each habitat to support the weight of spiders there, based on spiders’ known food requirements per unit of body weight. That done, they extrapolated their habitat-based results to the whole planet, in light of what is known about the total areas of such habitats.

这周发表在自然科学杂志的研究中，瑞士伯尔尼大学的Martin Nyffeler和瑞典隆德大学的Klaus Birkhofer尝试在蜘蛛的饮食习惯上做标号。以现有的数据开始，在地球上主要栖息地（森林、草地、田地等等）每平方米发现的蜘蛛，他们计算了为了维持每个栖息地的蜘蛛总体重恒定不变所需要的猎物数量，因为我们已经知道蜘蛛每单位体重的食物需求量。试验完成后，根据已知的这样的栖息地的总面积，他们推测对于整个星球来说它们基于生境的结果。

•  Prey猎物

• Extrapolated 推断，外推

Their conclusion was that there are 25m tonnes of spiders around the world and that, collectively, these arachnids consume between 400m and 800m tonnes of animal prey every year. This puts spiders in the same predatory league as humans as a species, and whales as a group. Each of these consumes, on an annual basis, in the region of 400m tonnes of other animals.（读者试译）

他们计算出在世界范围内有2500万吨的蜘蛛，而且，这些蜘蛛纲节肢动物每年总共捕食400-800百万吨的动物。这使得蜘蛛与人类这一物种处在同一个掠夺性的联盟总，并且和鲸鱼为一个类别。（期待您的翻译，明天会有针对这句话的长难句解析哟~）

•  predatory league  掠夺性联盟

Somewhere between 400m and 500m tonnes is also the total mass of human beings now alive on Earth. Approximately speaking, then, Bristowe was right. Arachnophobes, meanwhile, should consider this: without spiders, there would be an awful lot more other creepy-crawlies around.

对于生活在地球上的人类来说，400-500百万吨的食物也是人类维持生存所必须的。大致说来， Bristowe的猜想是对的。同时，对于蜘蛛恐惧症的人来说，如果没有蜘蛛，那就会有更多的其他的爬行动物，那将会更加可怕。

翻译 ▍E-K-2

审核 ▍云图

编辑 ▍璃儿