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为什么死虫总是背部朝下 – 译学馆
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为什么死虫总是背部朝下

Why are Dead Bugs Always on Their Backs?

科学秀
为什么死虫总是背部朝下?
You might notice something odd about those flies you just swatted,
你可能会注意到刚拍死的苍蝇
or the cockroaches you nuked with insecticide.
或是死于杀虫剂的蟑螂很奇怪
It seems like they almost always wind up on their backs.
他们似乎总是背部朝下死去
And that’s not your imagination.
这不是你的幻觉
Dead bugs really do end up belly up quite often
由于物理学和生物学的共同作用
Thanks to a combination of physics and biology.
死虫子真的经常腹部朝上
If you think about the shape of your typical insect,
如果你回想一下常见昆虫的形状
like a cockroach or fly,
比如蟑螂或苍蝇
it’s rounded with fairly thin legs relative to its body.
和圆形的身体比起来 它的腿非常细
That means most of its body weight
这意味着它的体重
is concentrated near the top of its body,
大多集中在顶部附近
so it has a high center of mass.
因此它有很高的重心
That’s the point of an object
那是重力这类外力
where external forces like gravity appear to act.
在一个物体上的作用点
And the higher it is,
重心越高
the less tilt is required
昆虫就越不能倾斜
before it’s no longer over the object’s base
当重心不再在这个物体上
—at which point the object or insect, in this case, topples.
这个物体 比如我们说到的昆虫 就会翻倒
In fact, many bugs would just tip over
事实上 如果不是因为它们的腿部肌肉在持续工作
if it weren’t for the constant work of their teeny leg muscles
昆虫就会翻倒
—they’re pretty much always doing a push up to stay upright.
它们总是向上撑着以保持直立
Sure, a bug will occasionally stumble onto its back
当然 虫子偶尔也会仰面摔倒
or purposely roll over as a defense mechanism.
或为了保护自己而故意翻滚
But whenever it finds itself in a supine position,
但当它发现自己处于仰卧位置时
it can right itself with a little coordinated leg or wing action.
它可以通过腿或翅膀的动作 来协调自己
There’s even one family of insects called click beetles
甚至还有一个叫“扣头甲”的昆虫家族
that launch themselves into a somersault to land right away up again.
它们会翻筋斗 以便着地时直接“正”过来
But that all kind of falls apart
但所有摔伤的情况
when an insect is injured or sick
都是因为昆虫受伤或生病
because it loses the ability to perform complex muscular movements.
从而失去了进行复杂肌肉运动的能力
I mean, just picture trying to do a cartwheel
我是说 想象一下在你得了流感
when you’ve got the flu or a broken arm.
或手臂受伤时推手推车的情形
And any weakness in those leg muscles
如果腿部肌肉无力
and they’ll naturally curl inwards,
它们就会自然向内弯曲
a bit like how your fingers curl when you rest your hand.
有点像你手部放松时弯曲的手指
Curled legs can’t support that top-heavy body.
弯曲的腿支撑不了沉重的上身
The chemicals used to kill bugs
杀虫的化学药剂
also usually mess with their nervous system directly.
也常常会干扰它们的神经系统
Insecticides generally contain neurotoxins,
杀虫剂通常含有神经毒素
like organophosphates or pyrethroids,
例如有机磷酸酯和拟除虫菊酯
which cause convulsions or paralysis in insects
它们通过过度刺激或抑制昆虫的
by over-stimulating or inhibiting their neuronal signals.
神经信号 从而引起昆虫抽搐或麻痹
Either way, the loss of muscular coordination combined
无论哪种方式 肌肉失去协调能力
with a high center of mass
加上重心偏高
means the animal probably ends up on its back before it dies.
意味着昆虫在它死前可能会翻倒
In fact, if you see a bug on its back,
事实上 如果你看到虫子翻倒了
it’s likely not long for this world.
那么它可能活不长了
In a 2002 study on Mediterranean fruit flies,
在2002年对地中海果蝇的研究中
researchers found that as flies aged,
研究人员发现随着果蝇年龄的增长
they were more likely to go belly up temporarily
它们的肚子很可能暂时大起来
—and when that happened,
这就导致
their chances of dying jumped by close to 40 percent.
它们的死亡概率增加了近40%
Bugs pretty much never choose to be supine
虫子几乎从不躺着
unless they’re playing dead,
除非他们装死
so their inability to get up quickly
因此它们无法快速翻身
is probably an indicator that something is wrong.
就预示着可能是出问题了
Thanks to our patron Carol for asking,
感谢赞助人卡罗尔的提问
and to all our other patrons
也感谢我们的其他所有
that voted for this question in our Patreon poll.
参与了Patreon投票的支持者
If you want to suggest questions like this one,
如果你也想这样提问
vote on which questions we should answer,
请投票决定我们回答的问题
or just get some really cool rewards like exclusive blooper reels,
或想得到像独家彩蛋一样酷的报酬
you can head over to Patreon.com/SciShow
你可以登录Patreon.com/Scishow
to learn more about becoming one of our patrons.
去了解怎样成为我们的支持者之一

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解释了死亡的虫子为什么总是背部朝下

听录译者

收集自网络

翻译译者

千寻1997

审核员

审核员 RN

视频来源

https://www.youtube.com/watch?v=Gk-B4baggkA

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