However, a recent discovery suggests that there are exceptions to this rule.
Deep in the cool waters of the oceans lives a very large fish called opah. The strange aspect about this fish is that, even though it lives hundreds of feet deep in the water, where the temperature is very low, this species of fish has the special ability of regulating the temperature of its body, keeping it warm.
The researchers detailed the new findings in the journal Science Advances.
Nicholas Wegner, a researcher at the National Oceanic and Atmospheric Administration (NOOA) and one of the authors of the study, explained that the recent discovery of the first warm blooded fish changes what the scientists knew about the process of endothermy.
This process is responsible for warming the body of the animals in order to keep them comfortable in cold environments.
According to Wegner, the experts believed that only mammals and birds have this unique ability of warming their own bodies, but apparently, some species of fish also have it.
And adult opah fish can usually weigh up to 100 pounds, but it can also weigh more than double this size.
Wegner said that these fish swim in the oceans using their pectoral fins in a move similar to the flapping of a bird’s wings.
The opah fish almost resembles a penguin when it swims, Wegner added.
These fish have large pectoral muscles, much larger compared to other species of fish.
As they swim, the pectoral muscles of the opah fish generate heat. For the majority of fish species, keeping the temperature of their bodies high while swimming in deep, cold waters is not very easy.
Biologists say that it’s very hard for fish to maintain their body warmth because their blood is very close to the water when this moves through the fish’s gills.
But the opah fish has found a way to adjust this: it can minimize the heat loss by placing the blood vessels responsible for carrying the warm blood from the muscles and position it near the vessels that carry the cold blood away from its gills.
This way, the warmth of the blood that comes from the muscles is repositioned to the colder blood that comes from the animal’s gills.
This process allows the fish to increase the temperature of the whole body, including important organs, like the heart.
Image Source: marinecreations