Biology: Antarctic Icefish

The Antarctic Icefish are a cold colored, cold blooded group fish from the cold waters around Antarctica. Most live at seawater temperatures between of –2°C and 4°C, but some sub-polar species inhabit waters that may be as warm as 10°C around New Zealand and South America.

But at –2°C wont water freeze? Well, freshwater would freeze, but the salt in seawater gives it a lower freezing point.

The reason icefish don`t freeze is because the blood contains a natural anti-freeze. Also, icefish only have 1% hemoglobin in their blood as opposed to the 45% in most animals. Because of this their the fish appears ghostly white. These fish are able to survive without large amounts of hemoglobin in part because of the high oxygen content of the cold waters of the Southern Ocean, and in part because oxygen is absorbed and distributed directly by the plasma. It eats small fish and krill.

Sources: Wikipedia
(Book) Ocean by The American Museum of Natural History.