2. Antarctic Icefish
Antarctic icefish are unique among vertebrates, lacking hemoglobin in their blood. To survive in subzero waters, they produce antifreeze glycoproteins that prevent ice crystal formation in their bodies. These specialized proteins bind to ice crystals, inhibiting their growth and allowing the fish to thrive in the icy Southern Ocean. This adaptation has been crucial for their survival as Antarctic waters cooled dramatically over millions of years. (utmsi.utexas.edu)