Lauren: Scoring that prime beach spot can be tough.

Everyone’s fighting for the best real estate.

These Black… back… um… Blackback...land… These, uh, crabs, come from the Dominican Republic.

They live in dense colonies on the beach.

Each male establishes a territory and defends a burrow -- with a pretty impressive set of claws.

Those claws have serrated edges.

And they sure can pinch.

The goal here is basically to tear your opponent limb from limb.

Every joint is a potential weak spot.

This guy is already at a disadvantage.

With that broken claw, his flank’s open to attack.

When his opponent goes for a leg… Yowch!

But don’t worry.

It’s not as bad as it looks for him.

See how the leg comes off cleanly, right here?

There’s a seam where two of the upper leg segments meet.

He let it go, on purpose.

That’s how these crabs cry uncle.

By the end of the fight, he’s lost six of his eight legs.

Awkward… He can barely get back to his den like the rest of the crabs do at the end of the day.

But he’s not stuck that way.

Losing legs is pretty normal around here.

Within a week, they begin to regrow.

New limb buds sprout in the open sockets of his shell.

Each is a complete leg in miniature, all coiled up inside a thin sac.

But to really get back on his feet, the crab will have to start fresh.

Don Mykles at Colorado State University studies what happens next - the process called molting.

Crabs wear their hard skeletons on the outside, but underneath their soft bodies are always growing.

So, they have to go through one crazy-looking growth spurt.

Normally, it happens about once a year.

But this is an emergency.

For the next eight weeks in its den, the crab secretes enzymes under its shell that start the separation process.

And it begins to build a new shell in a paper-thin layer under the old one.

Then, the crab packs up and moves out.

He gulps air into his body to create enough internal pressure to pop the top of his old shell.

Then, he slides himself out the back and unfurls those new legs.

His body is still flexible.

In a restaurant, he’d be called soft-shell crab right now.

A couple of weeks, and his new shell will harden, then, he’ll be ready for a rematch.

As in, blackback land crab … payback.

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Lauren: So the gland that actually controls molting is in the crab’s eyestalks, which explains why they’re so well protected.

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