Science_Illustrated_Australia_-_Issue70_2019

By Lea Milling Korsholm & Lars Thomas

Electric cells

to paralyse prey

The South American electric eel can generate up to 600 volts

which it uses for both defence and attack. The powerful

discharges can leave even large animals unconscious,

allowing the eel to consume them at leisure – or take flight.

1

The eel’s electric organs

consist of flat, disc-shaped

cells, electrocytes, that

are stacked very closely together.

2

Biological pumps in

e lec tro cyt e cel l mem branes

send negatively-charged ions

out of the cell and positively-charged

ions into the cell, causing a voltage

difference of about 0.1V between the

outside and the inside, converting

the cell into a small battery.

3

When the eel wishes

to emit a shock, nerves

release neurotransmitting

acetylcholine. This makes the

closest electrocytes fire their

0.1V spark, influencing the next

ones in the sequence to do the

same thing, creating a wave.

4

The wave of firing flows

through the animal's

entire body in a mere

two milliseconds. An adult

electric eel may have some 6000

electrocytes, so if they are all

influenced and fired, the result

can be a shock of around 600V.

An adult eel has around 6000

electrocytes, each creating 0.1 volt,

so a full firing can result in a total

delivery of around 600 volts.

CLAUS LUNAU & NORBERT WU/MINDEN/RITZAU SCANPIX

Electrocyte

Electrocytes

Nerve

Acetylcholine

Negative ion

Biological pump

Positive ion