Name: 【TED-Ed】魚如何產生電? (How do fish make electricity? - Eleanor Nelsen)
Uploaded: 2017-11-30T22:30:31.000Z
Duration: 5 min 15 s

In 1800, the explorer  Alexander von Humboldt

1800年，探險家亞歷山大-馮-洪堡。

witnessed a swarm of electric eels leap out of the water

反身代名詞

to defend themselves  against oncoming horses.

Most people thought the story so unusual that Humboldt made it up.

大多數人都認為這個故事很不尋常，所以洪堡編造了這個故事。

But fish using electricity is more common than you might think;

and yes, electric eels are a type of fish.

electrical signals offer ways to communicate,

and find—plus, in rare cases, stun—prey.

和發現加，在極少數情況下，眩暈捕獵。

Nearly 350 species of fish have specialized anatomical structures

that generate  and detect electrical signals.

depending on how much  electricity they produce.

Scientists call the first group the weakly electric fish.

Structures near their tails  called electric organs

produce up to a volt of electricity, about two-thirds as much as a AA battery.

產生的電量可達1伏，約為AA電池的三分之二。

The fish's brain sends a signal through its nervous system to the electric organ,

魚'的大腦通過神經系統向電器官發出信號。

or thousands of disc-shaped  cells called electrocytes.

或數以千計的盤狀細胞，稱為電細胞。

Normally, electrocytes pump out sodium and potassium ions

正常情況下，電細胞會泵出鈉離子和鉀離子。

to maintain a positive charge outside and negative charge inside.

以保持外面帶正電，裡面帶負電。

But when the nerve signal arrives at the electrocyte,

Now, one face of the electrocyte is negatively charged outside

現在，電細胞的一個面在外面帶負電。

But the far side  has the opposite charge pattern.

但遠方的電荷模式卻與之相反。

These alternating charges  can drive a current,

turning the electrocyte  into a biological battery.

The key to these fish's powers  is that nerve signals are coordinated

這些魚的能力的關鍵是神經信號的協調性

to arrive at each cell  at exactly the same time.

That makes the stacks of electrocytes act like thousands of batteries in series.

這使得堆積的電細胞就像成千上萬的電池串聯起來一樣。

The tiny charges from each one add up to an electrical field

每個人身上的微小電荷加起來就是一個電場。

Cells called electroreceptors buried in the skin

埋在皮膚裡的細胞叫電感受器。

allow the fish to constantly sense this field

and the changes to it caused  by the surroundings or other fish.

以及周圍環境或其他魚類對其造成的變化。

The Peter’s elephantnose fish,  for example,

has an elongated chin called a schnauzenorgan

That allows it to intercept signals from other fish,

這使得它可以攔截其他魚類的信號。

detect the shape and size of nearby objects,

and even determine whether a buried insect is dead or alive.

甚至可以確定被埋的昆蟲是死是活。

But the elephantnose and other weakly electric fish

don't produce enough electricity to attack their prey.

不要'產生足夠的電力來攻擊它們的獵物。

That ability belongs  to the strongly electric fish,

of which there are only  a handful of species.

The most powerful strongly electric fish is the electric knife fish,

Three electric organs span almost its entire two-meter body.

三個電機關幾乎橫跨了它整個兩米的身體。

the electric eel uses its signals to navigate and communicate,

電鰻用它的信號來導航和交流。

but it reserves its strongest  electric discharges for hunting

但它為狩獵保留了最強的電擊能力

using a two-phased attack that susses out and then incapacitates its prey.

使用一個兩階段的攻擊，發現，然後使其獵物喪失能力。

First, it emits two  or three strong pulses,

These stimulate the prey's muscles, sending it into spasms

這些刺激獵物的肌肉，讓它進入痙攣狀態'。

and generating waves  that reveal its hiding place.

併產生波瀾，暴露其藏身之處。

Then, a volley of fast,  high-voltage discharges

然後，一連串的快速高壓放電。

causes even more intense  muscle contractions.

The electric eel can also curl up so that the electric fields

generated at each end  of the electric organ overlap.

The electrical storm eventually exhausts and immobilizes the prey,

電風暴最終將獵物耗盡並固定下來。

and the electric eel  can swallow its meal alive.

The other two strongly electric fish are the electric catfish,

with an electric organ  that occupies most of its torso,

有一個佔據其大部分軀幹的電動器官。

and the electric ray, with kidney-shaped electric organs on either side of its head

There is one mystery in the world of electric fish:

在電魚的世界裡，有一個謎團。

It may be that the size  of strongly electric fish

allows them to withstand their own shocks,

or that the current passes out  of their bodies too quickly.

或者說電流過快地從他們的身體裡流走。

Some scientists think that special  proteins may shield the electric organs,

一些科學家認為，特殊的蛋白質可能屏蔽了電器官。

but the truth is, this is one mystery  science still hasn't illuminated.

但事實是，這是一個神祕的科學仍然沒有'照明。