Well, if we consider the basic factor to acquire great speed and not faint for long periods of time, there is no color: the fish. That differential element is respiration.
The gold medal has been awarded by a team of researchers from the Center of Excellence for the Study of Coral Reefs, belonging to James Cook University, in Australia. According to his research on rainbow trout ( Oncorhynchus mykiss ), published in the journal Plos One , the large family of fish is by far the best at releasing oxygen from tissues. Compared to humans, they do it 50 times more efficiently.
This advantage is due to the special characteristics of its hemoglobin, the protein in the blood responsible for transporting oxygen, in its case much more sensitive to changes in pH. Thus they can double and even triple the release of the vital gaseous chemical element in stressful situations, when they have to escape from predators, or if they live in waters with low oxygen levels. It is the secret weapon of species that travel long distances, such as salmon, or of born sprinters such as tuna.
