Book 18, Question 61
How Can Some Fish Live in Water That Is Colder than Freezing?
Some fish can live in water colder than freezing because they make their own antifreeze! The antifreeze is made of special proteins in their blood and body fluids. It keeps tiny ice crystals from growing, so the fish keep swimming happily.
More fun facts
- Salty ocean water rarely freezes except in the polar regions.
- Polar fish have special antifreeze proteins in their blood.
- These proteins stick to tiny ice crystals and stop them from spreading.
- Ice floats, so fish can swim freely in the cold water under a frozen surface.
- In very cold fresh water, fish often gather near the bottom, where water is slightly warmer.
Sources: Smithsonian Magazine, NOAA Ocean Service
Questions kids ask
How do antifreeze proteins work?
They stick to tiny ice crystals in a fish's blood and stop them from spreading.