How a tiny worm survives in Great Salt Lake water

HostIf you ever visit the Great Salt Lake, you notice right away that it's a pretty harsh place. Most of the things we think of as normal for a lake, like fish or lily pads, just can't handle how salty it is. For a long time, we thought only a few types of flies and some tiny shrimp could survive there.

HostHow does a tiny worm manage to live in water that would kill almost anything else?

GuestIt's a bit of a shock, really. These worms are roundworms, and they're so small you can't see them without a lens. They're everywhere on Earth, but nobody expected them to be at the bottom of a lake that's sometimes six or seven times saltier than the ocean. To most life, that's not just a lake; it's a bowl of poison. The main problem is what salt does to water. Salt acts like a sponge that wants to pull water toward it. If you put a normal cell in that lake, the salt on the outside would suck all the water out of the cell until it shrivels up and dies. It's like the lake is trying to turn everything into jerky.

HostSo the worm is in a constant tug of war just to keep its own insides from being sucked out?

GuestIt's a fight for every drop of water it has. These worms have a few tricks to win that fight. First, they have a very tough outer layer that acts like a seal to keep the water in, but even that's not enough. The real magic happens inside their cells. They make a lot of a special kind of thick, sugary fluid. You can think of it like a syrup that stays inside them. This syrup creates its own pull. By keeping their insides just as thick and heavy as the salt water on the outside, they stop the water from leaving. They balance the scales so the lake can't steal their moisture. It's a bit like having a shield made of sugar that keeps the salt from winning the tug of war.

HostBut if they're making themselves that thick on the inside, wouldn't that mess up how their bodies work? Our own cells need a very specific balance to stay alive.

GuestIt would be a total disaster for us, but these worms are built differently. Their inner parts are made to work even when they're packed with that syrup. They're not just barely getting by; they're doing great. They spend their time eating the tiny bits of life like bacteria that also manage to grow in the salt. But there's another layer to this. These worms don't just swim in the open water where the shrimp are. They live deep down in the mud at the very bottom of the lake, tucked away where the water is heaviest.

HostThat sounds even worse than the water. Isn't the mud at the bottom of a salt lake full of stuff like sulfur? It must smell like rotten eggs down there.

GuestIt does. It's a very dark, smelly, and tough place to be. There's almost no air down there, which is another huge hurdle. So these worms aren't just fighting the salt; they're also living without the oxygen that most animals need to breathe. We used to think the bottom of the lake was a dead zone. We figured it was just too much for anything with nerves and a gut to handle. But when researchers took some of that mud and looked at it under a strong light, they saw thousands of these little guys wiggling around. They have found a way to breathe using different chemicals in the mud that would be toxic to us. They have turned a wasteland into a home.

HostI'm still stuck on the salt. If I took one of these worms and put it in a normal glass of tap water, what would happen?

GuestThe tug of war would flip instantly. Now, the water from the tap would go rushing into the worm because the worm’s insides are so much thicker than the fresh water. It would swell up like a balloon and likely pop. They have become so good at living in the extreme salt that they can't go back to the world we think of as normal. They're locked into their salty home. They have traded the ability to live anywhere else for the ability to live where no one else can bother them.

HostWhy go to all that trouble? Is there some big payoff for living in a place that's trying to kill you every second?

GuestThe payoff is that nothing else can get to you. If you're a tiny worm in a regular pond, everything wants to eat you. Small fish, bigger bugs, and other hunters are always on the lookout. But in the Great Salt Lake, there are no fish. There are no big hunters in that deep mud. It's a safe haven. If you can solve the salt problem and the air problem, you have the whole place to yourself. You have all the food and all the space you could ever want without ever having to run away from a predator. It's a lonely life, but it's a very safe one.

HostSo they give up the easy life in fresh water to be the kings of a world made of salt and mud.

GuestIt's a survival trade that might even exist on other worlds, since we know some moons in deep space have huge, salty oceans hidden under miles of ice.

HostThe Great Salt Lake might look like a dead sea from the shore, but those tiny worms are busy making a life in the deep, salty mud.