Crocodile Icefish – The Fish With Almost Transparent Blood
The crocodile icefish or white-blooded fish are a family of perciform fish. It is found in the cold waters around Antarctica and southern South America. They feed on krill, copepods and other fish. Icefish reach a total length of 25–75 cm. In crocodile icefish, blood is colorless because it contains no hemoglobin. The fish can live without hemoglobin because of their low metabolic rates and the high solubility of oxygen in water at the low temperatures of their environment.
To compensate for the loss of hemoglobin, they have larger blood vessels, greater blood volumes, bigger hearts and greater cardiac outputs compared to other fish. Crocodile Icefish are the only known vertebrates without hemoglobin and an oxygen transport protein in the blood.