毛毛虫变身冰棍挺过严冬

Some caterpillars have evolved with antifreeze in their body cavities, allowing them to become cater-Popsicles to survive cold winters. But climate change could threaten that.

一些毛毛虫的体腔内进化出了防冻剂,这使它们变身为“冰棍”挺过寒冬。但气候变化可能会对此造成威胁。

So there are caterpillars that have been reported to be put into an ice cube and frozen, and then when the ice cube melts, they can get up and walk away.

据报道,将一些毛毛虫放进冰块里冷冻,待冰块融化时,它们仍能苏醒过来,四处爬动。

You may have seen them scooting around on leaf litter in the fall.

你可能见过它们在秋季的层层落叶上快速爬动。


They’re furry, rotund, and famous for their rumored weather forecasting skills.

它们毛茸茸、圆乎乎,以传言中的天气预报技能而闻名。

I’m talking about the woolly bear caterpillar, or Isabella tiger moth.

我说的是毛熊毛虫,也称作伊莎贝拉虎蛾。

These little creatures have an orange waistband stripe, whose width is rumored to predict how long winter might be.

这些小动物腰间盘有橙色条纹,据传,条纹宽度可以预测冬季有多长。

And while this is based in colonial folklore, not science, what is scientifically amazing is how the woolly bear caterpillar is able to survive winter.

虽然这是殖民地的民间传说,而非科学说法,但从科学上讲也很吃惊的是,毛熊毛虫是如何挺过冬天生存下来的。

I’m Kate Furby, and you’re listening to Science, Quickly.

我是凯特·弗比,您正在收听的是科学快报。

Unlike humans and other mammals, caterpillars can’t regulate their body temperatures.

与人类和其他哺乳动物不同,毛熊毛虫无法调节自己的体温。

And unless they burrow or cocoon, they’re subject to the wind and rain.

除非它们钻到洞里,要么做茧围住自己,否则它们只能任凭风雨吹打。

The woolly bear caterpillar, like its name, is covered in a spiky looking fuzz.

毛熊毛虫,虫如其名,身上裹着一层尖尖的绒毛。

Those hairs you might think of as a little down jacket for the caterpillar to wear, and I’m sure that they do provide a little bit of insulation.

你可以把毛毛虫身上的毛想象成它们身裹小件羽绒服,我相信它们确实提供了一点保暖效果。

That’s Dr. Martha Weiss, a biologist and professor at Georgetown University, who studies plant-insect interactions.

这是玛莎·韦斯博士,她是乔治敦大学的生物学家,也是这所大学的教授,她的研究内容是植物与昆虫的相互作用。

She says that spiky little caterpillar jacket has a specific use but not what you might think.

她表示,这种尖细的毛毛虫夹克有特定的用途,但不是你想的那样。

Those hairs are thought to have evolved as a way to protect the caterpillars against predators and maybe against parasitoids that wanna lay their eggs inside the caterpillar’s body.

一般认为,这些尖毛是为了保护毛毛虫免受捕食者的伤害,也许是为了对付那些想在毛毛虫体内产卵的拟寄生物而进化出来的。

Yikes, that is a superpowered little jacket actually. But here’s the caterpillar’s dilemma.

哎呀,这其实是一件超级强大的小夹克。但这也是毛毛虫的困境。

Well, the main thing is that it gets really cold, and they have a lot of water in them, and they can freeze. And so they need to be able to deal with freezing temperatures.

主要的问题是,天气会变得寒冷,绒毛里带有大量水会结冰。所以,它们需要能够应对冰点以下的温度。

And while the famous furry jacket provides protection, it doesn’t provide the kind of insulation woolly bear caterpillars need for a hard Chicago winter.

虽然了不起的毛茸茸外套提供了保护,但它并不能提供毛熊毛虫在芝加哥严冬所需的那种保暖效果。

What they do is a little more biochemical.

它们的操作更贴近生化反应。

They have more biochemical tricks up their sleeves insofar as caterpillars could be said to have sleeves.

它们的袖子里有很多生化诀窍,说得毛毛虫好像有袖子一样。

Oh wow, they would have to have like 16 little sleeves!

哇,那它们得有16个小袖子!

But okay, so what are their options for survival?

但是好吧,那么他们选择什么得以存活呢?

They can also do biochemical things and physiological things to make it less likely that they will turn into an ice cube.

它们还可以发生一些生物化学反应、生理变化,以降低它们变成冰块的可能性。

So what some of those caterpillars do is: they use antifreeze.

有些毛毛虫会用防冻剂。

They basically make compounds like glycerol that they put into their cells.

它们主要会制造出像甘油这样的化合物,然后将其放入细胞中。


In case you’re not familiar with glycerol, it’s a natural alcohol compound.

以防你不熟悉甘油,说明一下,甘油是一种天然的酒精化合物。

It works similarly to when we salt city sidewalks to keep them from becoming icy.

甘油的工作原理类似于我们在城市人行道上撒盐以防结冰。

The compounds in the woolly caterpillar’s body lower its freezing point, buying it some time. And then they do something even more remarkable.

毛毛虫体内的这种化合物可以降低体内冻结点,争取一些时间,让它可以做一些更了不起的事情。

They move water out of their cells so that it freezes in the extracellular space.

它们将水脱离出细胞,使其在细胞外空隙结冰。

That’s because ... Water of course gets bigger when it turns to ice.

那是因为……水结成冰时体积自然会变大。

And so if a cell was filled with water, and it froze, then it could bust the cell membrane, and that would really harm the caterpillar.

如果一个细胞里满是水且结冰了,那么细胞膜就会遭到破坏,这会危及毛毛虫的生命。

So getting the water out of the cell is a good idea, and lowering the temperature at which the liquid freezes is also a good idea.

将水排出细胞是一个好主意,降低液体结冰温度也是一个好主意。

So these little guys can freeze solid all winter and then thaw out and get up and walk away come spring.

这样,这些小家伙整个冬天都会冻得扎扎实实,到了春天,解冻、苏醒、四处爬动。

They can actually freeze and thaw multiple times over the course of a winter.

实际上,在冬季,它们会经历多次结冻与解冻。

But there’s an energetic cost that comes to falling asleep and waking back up again.

但是入睡与苏醒是个耗精力的活儿。

Studies of the Isabella tiger moth have shown that they can in fact undergo several freeze thaw cycles, but it’s really not great for them.

对伊莎贝拉虎蛾(毛熊毛虫)的研究表明,它们实际上可以经历几轮结冻与解冻,但这对它们来说并不好。

It’s better if they can freeze, stay frozen and then thaw at the end of the winter.

如果它们在冬季开始时结冻,保持这个状态,待到冬季结束时再解冻,那就更好了。

And not only that ...I think there’s also some damage that happens to some of the structures in the caterpillar.

不仅如此……我认为毛毛虫的部分结构也会受到一些损伤。

Some of the more delicate parts, I think, can be damaged a little bit.

我认为,一些比较脆弱的部分可能会有损伤。

And the more times they have to freeze, thaw and refreeze, the more likelihood that they'll be a little worse for wear at the end of the winter.

毛毛虫结冻、解冻、再结冻的次数越多,冬天结束时就越有可能遭受严重的损耗。

And this gets worse because of things like climate change.

由于气候变化等原因,情况愈发糟糕。

If we have winter heat waves or warm periods when caterpillars that had been in the deep freeze, thaw out and then freeze again, there was some concern that they wouldn’t be able to go back and forth between these conditions.

如果遇到冬季热浪或冬季温暖期,毛毛虫必须深度结冻、解冻、然后再次结冻,人们担心它们无法在这样的环境下自由变化。

That’ll also lead to larger ecological implications.

这也会导致更大规模的生态影响。

Caterpillar populations and therefore butterfly or moth populations could take a hit if the overwintering survival is interfered with by these interludes of warmer weather that prevent them from getting through their wintering period in the same way that they had before.

如果越冬生存受到这些穿插的温暖天气的干扰,进而阻止它们像以往一样越过冬季,那么,毛毛虫、蝴蝶、蛾子的数量可能会受到打击。

And that might have more profound impacts than we think.

这可能会产生比我们想象的更深远的影响。

We already know that some important pollinators, like bees and butterflies, are struggling to survive due to all kinds of human activities.

我们已然知晓,由于各种各样的人类活动,一些如蜜蜂与蝴蝶等重要的传粉昆虫正在艰难生存。

Caterpillars are important just because they’re such cool animals, but they also are a phase of the life cycle of lepidopteran, so moths and butterflies.

毛毛虫至关重要,因为它们很厉害,它们是鳞翅目昆虫生命周期的一个阶段,蛾与蝴蝶也是如此。

They are pollinators; they’re herbivores; they're food for birds and other organisms.

它们是传粉昆虫; 是食草动物; 鸟类和其他生物以它们为食。

And they’re just part of what makes the world fun to look at and live in.

它们让这个世界丰富多彩、趣味横生。

For Scientific American’s Science, Quickly, I’m Kate Furby.

感谢收听《科学美国人》科学快报,我是凯特·弗比。

来源:Scientific American

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