A New Zealand-US study has revealed that the Antarctic fish have evolved a method to cope up with the ice building up in their bodies due to the extremely low temperature of the Antarctic and the icy Southern Ocean waters.

The findings of the study revealed an evolutionary paradox that has enabled protein-bound ice crystals accumulate inside the bodies of the fish and resist melting even when temperatures warm. So, this adaptive evolution of anti-freeze proteins present in fish has enabled Antarctic fishes to survive in freezing seawater.

Dr. Clive Evans, of the School of Biological Sciences, said in a statement, "What we have found is that antifreeze proteins not only stop ice from growing inside Antarctic fishes, but they also stop it from melting".

He explained that the ice inside the fish is actually 'superheated' and so it remains stable above its expected melting point. This property helps in the binding of anti-freeze proteins with the ice crystal surface.

This is the first case of the existence of 'superheated ice' inside any living organisms. Researchers believe that the existence of this ice inside the body of the fish poses a significant problem considering the fact that the only known way to melt the internal ice is through warming of the freezing seawater they inhabit.

This warming is a rare case as the study of the data of more than a decade shows that seawater in Antarctica's McMurdo Sound had never reached temperatures that would melt all the superheated ice in the resident fish.

Scientists would further study the long-term temperature recorded from McMurdo Sound and this will help them study the responses of a wide range of Antarctic organisms as the waters warm in response to climate change.