The Book of Eels: Our Enduring Fascination with the Most Mysterious Creature in the Natural World

by Patrik Svensson

It’s located slightly northeast of Cuba and the Bahamas, east of the North American coast, but it is also a place in flux. The Sargasso Sea is like a dream: you can rarely pinpoint the moment you enter or exit; all you know is that you’ve been there.

In the west by the life-giving Gulf Stream; in the north by its extension, the North Atlantic Drift; in the east by the Canary Current; and in the south by the North Equatorial Current. Two million square miles in size, the Sargasso Sea swirls like a slow, warm eddy inside this closed circle of currents. What gets in doesn’t always have an easy time getting out.

This is where the European eel, Anguilla anguilla, is born. This is where mature eels breed in the spring and their eggs are laid and fertilized.

They’re called leptocephalus larvae and have a body like a willow leaf, flat and virtually transparent, only a few millimeters long. This is the first stage of the eel’s life cycle.

Swept up by the Gulf Stream, they drift thousands of miles across the Atlantic toward the coasts of Europe. It’s a journey that can take as long as three years; during this time, each larva slowly grows, millimeter by millimeter,

undergoes its first metamorphosis, transforming into a glass eel. This is the second stage of the eel’s life cycle.

When a glass eel reaches the coasts of Europe, it will usually travel up a brook or river, adapting almost instantly to a freshwater existence. This is where it undergoes yet another metamorphosis, turning into a yellow eel.

the glass eel is tender and fragile, the yellow eel is strong and sturdy. This is the third stage of the eel’s life cycle.

can swim through murky lakes and up tranquil streams, up wild rivers and through lukewarm ponds.

swamps and ditches. It doesn’t let circumstance stand in its way, and when all aquatic possibilities have been exhausted, it can take to dry land, slithering through moist brush and grass in pushes toward new waters that can last for hours.

there, year after year, and normally wanders within a radius of only a few hundred yards. If relocated by external forces, it will invariably return as quickly as it can to its chosen abode.

Eels caught by researchers, tagged with radio transmitters, and released many miles from their point of capture have been known to return to where they were first found within a week or two. No one knows exactly how they find their way.

When the temperature drops, it can lie motionless in the mud for long periods, utterly passive, and at times entangled with other eels like a messy ball of yarn. It is a nocturnal hunter. At dusk, it emerges from the sediment and starts looking for food, eating whatever it can find.

And it’s a long life. An eel that successfully avoids illness and calamity can live for up to fifty years in one place. There are Swedish eels who have made it past eighty in captivity.

It starts making its way back to the sea while simultaneously undergoing its final metamorphosis. The drab and indeterminate yellowish-brown of its skin disappears, its coloring grows clearer and more distinct, its back turns black and its sides silver,

The yellow eel becomes a silver eel. This is the fourth stage of the eel’s life cycle.

the silver eels wander back out into the Atlantic and set off tow...

its eyes grow larger and turn blue to help it see better in the depths of the ocean; its digestive system shuts down; its stomach dissolves—from now on, all the energy it needs will be taken from existing fat reserves—its body fills with roe or milt. No external interference can distract the eel from its goal. It swims as much as thirty miles a day, sometimes as deep as three thousand feet below the surface;

has been shown that a silver eel in captivity can live for up to four years without any nourishment at all.

But once an eel reaches the Sargasso Sea, it has, once again, found its way home. Under swirling blankets of seaweed, its eggs are fertilized. And with that, the eel is done, its story complete, and it dies.