Until now, we had believed that only mammals and birds possessed body warming techniques irrespective of the environment.
While we considered all species of fish to be cold-blooded, a new discovery has written of this belief, explaining that there exists warm blooded fish.
Scientists at the National Oceanic and Atmospheric Administration (NOAA) have now discovered prime warm-blooded creatures among the aquatic species, which can keep its body warmer even at deep phases of the sea.
Researchers made use of thermometers implanted in the body of the fish to measure its temperature, and also placed satellite tags to track its motion for months.
It was found that the Opah variety of fish was able to maintain the body temperature at 5degrees C warmer than the temperature of its surrounding environment.
This applied also to deeper depths of up to even 300m. The fish also managed to maintain its head region and heart at 3 degrees C warmer than water.
Findings discovered that these aquatic creatures used its pectoral fins to propel its motion forwards, unlike in other species which gains the motion by the wave motion of its body.
The constant flapping of this pectoral fins helps in the circulation of the heated blood across its body. And this is different from some other species like Tuna, which specifically heats up the distinct organs for gaining a swifter motion when predating.
The pectoral fins are also insulated from the cold water by a layer of fat in Opah. The discovery also led to the finding that the cold blood, flowing opposite from the gills, also gets warmed up due to the contact between vessels carrying hot and cold blood.
The increase in temperature of its organs like heart helps it to have deeper dives, and stay there for prolonged periods. Normal fish retrace back to the surface to keep its organs warm in such conditions.
A detailed study has been published in the Science journal.