What if you’re a fish in freezing water?

Well, a free-swimming ocean fish can migrate to a warmer part of the sea.

But if you’re a lake fish, you don’t have that option. Luckily, the properties of water make its solid form—ice—less dense than its liquid form.

As a lake freezes, the ice floats on the surface, insulating the water below and keeping most lakes—and the fish within them—from freezing solid.

You would still, however, be very cold. Lake fish have to lower their metabolism and enter a state called torpor to reduce their energy demands enough to survive the winter.

This is especially important in spring before the ice melts, when oxygen levels in the water trapped under the ice may be dangerously low.

And what if you’re the unlucky fish where it’s even colder? Fish in polar regions live in saltwater that’s around 28 degrees Fahrenheit—that’s below the freezing point of fish blood.

In that case, you’d need antifreeze in your veins. And polar fish have developed exactly that. They produce a glycoprotein that slows down water’s molecular motion to keep ice crystals from forming.

All pretty interesting if you’re a fish. But what if you’re not?

Medical researchers—and car makers—have teamed up to study fish antifreeze, looking for better ways to keep radiators from icing up and ways to keep human blood and tissue from being damaged by ice crystals when in deep storage. Pretty cool.