How do fish survive freezing cold water?

Today’s Video of the Day from the American Chemical Society series Reactions explains how fish manage to survive the freezing cold waters surrounding Antarctica.

Even though the water in this region rarely rises above freezing, the fish are equipped with a type of antifreeze in their blood.

The fish swallow tiny ice crystals from the seafloor that should freeze them from the inside out. However, the biochemical antifreeze lowers the internal freezing point of the fish so that it is below the surrounding waters, meaning that the fish literally cannot freeze. The explanation behind this is simply because heat does not easily pass through the ice. This slows down the process of freezing the waters. Fish body fluids can easily solidify when the water temperature drops below minus 5 degrees Celsius.

Most fish slow down and “rest” near the bottom during cold winter months. White Shoal Lighthouse in northern Lake Michigan. Have you ever wondered how fish survive in cold winter weather, or where they go when lakes and ponds freeze over?

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By Chrissy Sexton, Earth.com Staff Writer

Video Credit: American Chemical Society