演讲题目：Let us ruin your day with this tongue-eating parasite

演讲简介：

臭名昭著的食舌虱是鱼类寄生虫科近400个物种中的一种。有些会依附在宿主的头部，有些会从鱼鳃吸食血液，还有些会钻进鱼的肉体。但缩头鱼虱（Cymothoa exigua）专门攻击鱼的舌头。这些寄生虫是如何做到的呢，又为什么要这样做呢？尼科・兹洛特尼克（Niko Zlotnik）探究了这些食舌寄生虫用来找到一个能让它们安身的鱼的策略。



中英文字幕

One night in 2013,

2013年的一个晚上，

a man in Northern Ireland was shocked to discover something bizarre protruding from the mouth of the sea bass he was preparing for dinner.

北爱尔兰的一名男子震惊地发现他正在准备晚餐的鲈鱼嘴上突出了一些奇怪的东西。

Peering closer, he came face-to-face with none other than the infamous "tongue biter," also known as the tongue-eating louse.

走近一看，他见到的不是别人，正是臭名昭著的“咬舌者”，也被称为吃舌虱子。

This species, Cymothoa exigua, is one of nearly 400 belonging to a family of fish parasites called cymothoids.

该物种名为Cymothoa exigua，是一个名为Cymothoids的鱼类寄生虫科近400种之一。

They're crustaceans, and more specifically, isopods, like pill bugs.

它们是甲壳类动物，更具体地说，是等足类动物，就像药丸虫一样。

Some latch onto their host's head, others suck blood from fish gills,

有些则咬住宿主的头部，另一些则从鱼鳃中吸血，

and still others burrow into fish flesh and form sac-like membranes around themselves.

还有一些会钻入鱼肉中并在自己周围形成囊状膜。

Clearly, there are many delightful ways to be a cymothoid,

显然，有很多令人愉快的方式成为一个cymothoid，

but Cymothoa exigua and others go specifically for fish tongues— or at least what pass as tongues among fish.

但Cymothoa exigua和其他物种专门针对鱼舌--或者至少是鱼舌。

Because instead of what we think of as a tongue, fish have a bony structure called a basihyal, protruding from the floor of their mouths,

因为鱼不是我们所说的舌头，而是有一种称为舌骨的骨质结构，从口腔底部伸出，

which they use to move oxygen-rich water towards their gills and to swallow food.

它们用它将富氧水移向鳃并吞下食物。

Tongue biters start out looking for a fish to call home for life, which can be up to around three years.

咬舌者开始寻找一条可以终生称为家的鱼，这可能长达三年左右。

They may swim for days, surviving off stored yolk reserves— until finally,

它们可能会游泳几天，靠储存的蛋黄储备生存--直到最后，

they sense a change in the light and pick up on a nearby fish's chemical cues.

它们能感觉到光线的变化，并捕捉到附近鱼类的化学信号。

They burst into action, hook onto the fish's gills using the sharp, curved tips of their limbs, and crawl on in.

它们突然行动起来，用锋利而弯曲的四肢尖端钩住鱼的鳃，然后继续爬进去。

There, they molt, and since they won't be living independently again, their eyes recede and their limbs lose their hair-like swimming structures.

在那里，它们会脱毛，由于它们将无法再次独立生活，它们的眼睛会后退，四肢也失去了毛发状的游泳结构。

Meanwhile, their sperm producing and transporting organs also mature.

与此同时，它们的精子生产和运输器官也成熟。

If they've moved into a fish that doesn't already have a tongue biter at the helm,

如果它们进入了一条掌舵处还没有咬舌的鱼，

they'll speed right through this male phase and develop into a female.

它们会快速通过这个雄性阶段并发育成雌性。

They grow much larger, their testes shrink, their ovaries become active, they form a kangaroo-like brood pouch,

它们变得更大，睾丸缩小，卵巢变得活跃，形成袋鼠般的育儿袋，

and they enter their host's mouth and clamp down on its basihyal.

它们进入宿主的嘴里并夹住其舌骨。

Here, they're thought to suck blood from the fleshier part of the fish's tongue-like structure.

在这里，它们被认为是从鱼的舌头状结构的肉质部分吸血。

Over time, the isopod's habits can cause the fish's basihyal to wither away,

随着时间的推移，等足类动物的习惯会导致鱼的舌骨萎缩，

leaving the fish with a parasitic crustacean acting as a tongue like appendage.

给鱼留下寄生甲壳类动物作为舌头状附属物。

In this form, the tongue biter is suspected to functionally replace the basihyal, moving food and water through the fish's mouth.

在这种形式下，咬舌鱼被怀疑在功能上取代了舌骨，通过鱼的嘴里运送食物和水。

Only mature female tongue biters take hold of the basihyal, and only one at a time gets a taste.

只有成熟的雌性咬舌者才能抓住舌骨，并且一次只有一个人尝到味道。

In the event that a few tongue biters share the same lucky fish and the tongue is already taken,

如果几个咬舌者共享同一条幸运鱼，并且舌头已经被拿走，

the others will remain male till the opportunity to switch arises.

其他人将保持男性身份，直到有机会转变。

If the female dies, a nearby male can develop into a female and fill the recently vacated position.

如果雌性死亡，附近的雄性可以发育成雌性并填补最近空出的位置。

Otherwise, males mostly remain in the gills, though they may climb into the mouth to mate.

否则，雄性大部分留在鳃里，尽管它们可能会爬进嘴里交配。

And when that happens, a female can produce hundreds of tiny tongue biters,

当这种情况发生时，雌性可以产生数百个微小的咬舌者，

carrying them inside a special pouch until they're ready to swim off and find fish of their own to make home sweet home.

将它们装在一个特殊的袋子里，直到它们准备好游泳并找到自己的鱼，让它们成为甜蜜的家。

Fish can survive years parasitized by cymothoids, but it may come as no surprise that having a blood-sucking isopod for a tongue isn't ideal.

鱼可以在食蟹类动物的寄生下存活数年，但舌头上有吸血等足类动物并不理想，这也就不足为奇了。

While some seem largely unaffected aside from the obvious, localized damage, others grow slower, become anemic,

虽然除了明显的局部损伤外，有些似乎基本上未受影响，但另一些则生长得较慢，变得贫血，

and are more susceptible to environmental stressors.

更容易受到环境压力的影响。

Parasitism rates can get surprisingly high among cymothoids' preferred hosts, which includes snappers, trout,

在食蟹动物的首选宿主中，寄生率可能会出奇地高，其中包括笛鲷、鳟鱼，

and croakers— also commonly consumed by people.

和鲑鱼--也是人们常食用的。

Surveys of Mediterranean striped sea breams and South African large spot pompanos found that nearly half the fish carried cymothoids in their mouths.

对地中海条纹海鲷和南非大鳍鲷的调查发现，近一半的鱼嘴里含有食蟹猴。

And the number can climb even higher in fish farms.

在养鱼场，这个数字可能会攀升得更高。

They're normally removed, but they've occasionally made their way into grocery stores and home kitchens.

它们通常会被拿走，但偶尔也会进入杂货店和家庭厨房。

And while theoretically eating a tongue biter doesn't pose any health risks, it might not be the most pleasant surprise.

虽然理论上吃咬舌者不会对健康构成任何风险，但这可能不是最令人愉快的惊喜。

What?

什么？

Louse got your tongue?

虱子咬了你的舌头？