A unique group of fish that has evolved to live in Antarctic waters thanks to anti-freeze proteins in their blood and body fluids is threatened by rising temperatures in the Southern Ocean, according to a new study by Yale. The development of antifreeze glycoproteins by notothenioids, a fish family that adapted to newly formed polar conditions in the Antarctic millions of years ago, is an evolutionary success story. The three species of fish are an example of the diversity this lineage achieved when it expanded into niches left by fish decimated by cold water environment. Now the same fish are endangered by warming of the Antarctic seas.