Chaotic, turbulent, harsh ...

The ocean's edge ... isn't the easiest place to make a home.

And yet, someone one does.

Pacific mole crabs - also called sand crabs.

You've probably seen the little holes they make.

They spend their lives just under the surface of the sand, waves crashing overhead.

That ever-present flux offers a meal.

Each wave kicks up plankton and other tasty morsels, like a 24/7 buffet.

They peep out from below the sand and use their feathery antennae to catch food right out of the water.

But they can't just sit around gorging themselves all day.

The crabs want to stay in the swash zone - this part here where the waves break and sweep in.

But it's always moving with the tides, up and down the beach.

So the mole crabs have to move with it.

But they're not the only ones here looking for a meal.

To birds, they're basically beach candy - easy pickings.

So mole crabs have become champion diggers.

They can disappear in a flash... back under the sand to hide.

But they have to be fast.

So, what makes them so good at burrowing?

Researchers at UC Berkeley want to find out.

Back at the lab, they film the mole crabs in action using high-speed cameras.

Mole crabs actually burrow backwards, digging into the sand with their pointy rumps.

But moving densely packed sand is hard work.

The grains stick to each other, making it tough to push through.

So they crabs become tiny engineers.

They stir up the wet sand with their tails making it easier to move.

A process called 'liquefaction.'

Then, they push the loose sand up toward the surface by handing it off between their five pairs of legs.

See?

Kind of like a conveyor belt.

The waves never rest, so the moles crabs do this day and night, as they're tossed and tumbled.

But they take it all in stride.

When you survive on chaos, fluidity is what it's all about.