At first glance, jellies seem like incredibly simple animals.

They don't have a heart, or blood, or even a brain.

They don't make decisions or work together.

They can't see or hear.

Basically, they just drift.

And yet... jellyfish have been around for at least six hundred million years.

Three times older than the dinosaurs.

They've survived five mass extinctions.

And you can find them in every ocean, from pole to pole.

So what's the secret to their success?

Keeping it simple, but with a few good tricks.

For example... jellyfish tentacles are lined with billions of cells called nematocysts, which sting and paralyze prey.

Jellies don't have brains to control these nematocysts, so each one acts independently.

It has its own trip wire.

When triggered, it fires a harpoon-like barb, laced with a powerful toxin.

It's one of the fastest mechanisms in the animal kingdom.

It explodes with an insane force - 10,000 times that of gravity.

Some jellies have another trick to lure prey.

See those bright green bulbs on the tentacles?

In daylight, they're kind of orange.

But under a blue light, they fluoresce to attract prey.

With tricks like these, jellies don't need to see their food - they just need to bump into it.

And when conditions are good, jellies reproduce like crazy - massive releases known as blooms.

They don't even need another jellyfish.

They can reproduce with a mate or without.

It's a pretty simple way of life, but it's worked for six hundred million years.

During that time, oceans have changed dramatically.

And jellies just kind of roll with it.

They're survivors.

Now the oceans are changing again.

Becoming warmer and more acidic.

At least some of the very conditions that endanger humans may suit jellies just fine.

Which means just as jellies were here long before us, good chance they'll outlive us too.

Wait, are you still there?

Look at this Jellyfish.

It is so freakin' beautiful.

I mean look at that thing.

And the reason I'm pointing this out is that filming things like this, Incredibly beautiful, often incredibly small things is the whole point of Deep Look.

It is, we think, what makes this show special.

And to do it, we need people like you to subscribe.

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And thanks a lot for watching.