(单词翻译:单击)
After a heavy rainstorm, you've probably seen worms popping out of the soil,
大雨过后,你也许能看到蠕虫类动物从泥土中钻出来,
getting stranded all over sidewalks and parking lots.
占领人行道和停车场 。
But between birds, clumsy humans, and the sun, it's dangerous for a worm to climb out of its safe, cozy burrow.
可是爬到满是鸟类、行人和阳光的陆地上,其实对于蠕虫类动物来说,爬出自己安全舒适的洞穴是很危险的 。
And yet they suddenly abandon ship whenever it starts raining.
但是一开始下雨,它们就突然弃船而逃了 。
Scientists have come up with plenty of possible reasons why rain might trigger this behavior.
科学家们提出了很多种可能解释为什么下雨会刺激它们的这种行为 。
But they don't quite agree on all of them.
但是他们并未达成一致意见 。
The oldest hypothesis -- and the one you might've heard -- is that earthworms surface to avoid drowning.
最古老的一种假设—你也许也听过—蚯蚓爬出来是为了避免溺水 。
That's because worms take in oxygen through their skin in a passive process called diffusion,
那是因为蠕虫以一种被动的过程—渗滤,从皮肤摄取氧气,
where oxygen moves from the higher concentration outside their bodies to the lower concentration inside.
在这种过程中氧气从身体外边的高浓度移动到内部的低浓度 。
When soil floods after a rainstorm, worms can usually still breathe if there's enough oxygen dissolved in the water.
雨后土壤被淹没,蠕虫还是可以呼吸,前提是水中有充足的氧气 。
But water is a lot denser than air, so diffusion is much slower -- like, up to 1000 times slower.
但是水比空气密度大,因此渗滤过程更慢—比如,其速度可以慢上1000倍 。
Which means that for a worm, it could be a lot harder to breathe after a downpour, which could make them rush to the surface.
对蠕虫来说,这意味着雨后呼吸更加困难,因此它们匆忙逃到陆地上 。
But some biologists have pointed out that plenty of worms can actually live for days submerged in water
但是一些生物学家指出,很多蠕虫可以潜入水中生活很多天,
although some of that may depend on the species.
但是这或许要取决于蠕虫的种类 。
One study published in 2008, found that two different species of worms use different amounts of oxygen.
2008年发表的一项研究发现,有两种蠕虫需要的氧气量不同 。
A common tropical worm uses relatively little, so it doesn't come up to the surface after it rains.
一种热带常见蠕虫需要氧气相对较少,因此这种蠕虫不需要在雨后爬上陆地 。
But another worm, the Alabama Jumper, needs more oxygen, especially at night, and it does surface.
但是另一种蠕虫Alabama Jumper,则需要更多氧气,尤其是在夜晚,而且它们确实会爬上陆地 。
So, there may be worms who do need to surface to breathe -- or at least prefer to -- while others don't.
所以有些蠕虫确实需要爬上来呼吸—至少它们更喜欢这样—而有一些则不需要 。
Other experts think worms might surface for different reasons.
其他专家认为蠕虫爬上来的原因并不相同 。
They argue that worms flee their burrows because rain gives them great travel conditions.
他们认为蠕虫逃离自己的洞穴是因为雨水给了它们更好的爬行环境 。
Earthworms move faster above ground, and they can crawl more quickly and safely when it's wet because they're less likely to dry out.
蚯蚓在地上快速移动,并且地面潮湿时,他们可以爬的更快也更加安全,因为它们不会被烤干 。
Some scientists have also proposed that worms take flooded soil as a cue to mate,
一些科学家也提出蠕虫将淹没的土壤当做交配的暗示,
possibly to increase their chances of finding a partner, but that seems to be limited to nightcrawlers and a few other species.
可能会增加它们寻找到另一半的机率,但是这似乎仅限于夜晚爬行者和几种其他种类 。
One last hypothesis is that raindrops landing on soil create vibrations similar to those
最后一种假设是落入土壤的雨滴创造了一种振幅,
made by one of the earthworm's biggest predators: the mole.
这种振幅和蚯蚓最大的敌人—鼹鼠所制造出的振幅一样 。
It's definitely true that earthworms will book it to the nearest exit if they sense certain tremors.
当蚯蚓感应到某种震颤时,它们会从最近的那个出口逃离,这绝对是真事 。
People actually exploit this by going worm grunting,
人们会通过一种worm grunting(通过声音抓蠕虫)的方式来抓蠕虫
where they catch worms to use as bait by driving stakes into the ground and vibrating them.
这种方法是将棍子插入途中并振动棍子,所抓到的蠕虫被用作诱饵 。
But experiments suggest that worms are only sensitive to vibrations that mimic moles, and that falling rain doesn't do the trick.
但是实验证明,蠕虫只对模仿鼹鼠的振幅敏感,雨滴并不管用 。
So, we may not know for sure why earthworms grace us with their presence after a storm,
因此,我们或许并不能够确定为什么蚯蚓会在雨后出现,
but at least we know what to do if we want to go fishing.
但是至少我们知道如果我们想去钓鱼该怎么办 。
Thanks to patreon patron Miranda McCarthy for asking this question, and thanks to all our patrons, who keep these answers coming.
感谢patreon赞助人Miranda McCarthy的提问,感谢所有赞助人一直向我们提问 。
If you'd like to submit a question to be answered, you can go to patreon.com/scishow.
如果你想提问,请登录patreon.com/scishow 。
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