Welcome to BrainStuff, a production of I Heart Radio.

Hey Brain Stuff, Lauren Bokelbaum here.

Every so often, yellow-bellied sea snakes tie themselves in knots.

They, like all serpents, must regularly shed their skin.

But the process demands friction, and in the open sea

it can be hard to find a rock or a reef to rub up against. So the animals

play contortionist. Twisting coils around coils they peel off old skin in an acrobatic

looping maneuver. The exercise has a nice side effect.

Barnacles, oysters, and other tiny hitchhikers plague these snakes.

Frequent sheds help keep their numbers down. If you're an armless,

armless legless airbreather, life in the ocean is fraught with challenges.

Yet the 50-plus sea snake species alive today use all kinds of amazing tricks to get by.

A snake at sea is not automatically a sea snake.

Lots of unrelated species frolic in our oceans from time to time.

Reticulated pythons, for example, will swim between islands along the coasts of southeastern Asia,

crossing distances that could wear out an olympian.

That doesn't, however, make them sea snakes.

When naturalists talk about sea snakes, they're usually referring to two very specific groups of reptiles that are part of the COBRA family,

true sea snakes, genus name Hydrophinee, and sea chrites or Laticotinae.

We've already mentioned one of the former species.

Yellow-bellied sea snakes, those oddball not tires, are classic hydrophyids.

True sea snakes like these have sworn off of dry land altogether.

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