9. Antarctic ice fish have blood with built-in antifreeze.
In oxygen-rich Antarctic waters, ice fish can survive and thrive in freezing waters. They have no hemoglobin, which is the oxygen-carrying protein that makes red blood cells red. In the absence of hemoglobin, the gills of ice fish appear white. The ice fish instead have special blood that contains proteins that act like antifreeze. The ice fish usually have ice crystals inside their bodies, and the special proteins work to ensure that the crystals do not grow in size. Surprisingly, researchers have found that ice crystals do not go away during the warmer summer months, which is one of the implications of living below the ice. This unique antifreeze protein is also found in a group of more than 120 fish that live in the Southern Ocean.