Meet the Arapaima, the Swimming Tank of the Amazon

(jazzy music)

[Narrator] If a tank could swim, and had scales,

and I guess eyes and stuff,

it would look like this.

The seriously armored and seriously huge arapaima

is a denizen of the Amazon.

It tops out at 440 pounds and 10 feet long.

Making it one of the biggest freshwater fishes.

The arapaima scales are marvels of evolutionary armament.

They're made of two layers.

The inside is a flexible collagen,

while the surface layer is mineralized.

This makes them pliable yet extremely tough.

And that's great news when you

share a river with a piranha

which is essentially just teeth

with a little bit of fish attached.

That's not the arapaima's only evolutionary trick.

Every so often, it comes to the surface and gulps air.

Yep, a fish with the gall to breath air.

But it makes sense.

In the Amazon, massive amounts of rotting vegetation

on the river bottom suck the oxygen out of the water.

So, breathing air not only lets the arapaima survive,

but it gives it a hunting advantage.

Any fish that doesn't take oxygen from the air,

will be much slower.

That makes them easy pickings for this apex predator.

And here we see several arapaimas hunting some

sort of stringy sky fish.

Ah, the wonders of the natural world.

(jazzy music)