Opah is hot-blooded! – Point

It is a discovery which should lead to a small update of biology textbooks. No, the fish are not necessarily cold-blooded animals. No, the ability to regulate body temperature globally and the length is not the exclusive domain of mammals and birds. Biologists NOAA – the National Oceanic and Atmospheric Agency US – have discovered that oprah, or kingfish-moon, a big flat fish and round depths of up to 2 meters long and 270 kg, was also this very well! The evolution even with this animal, nicknamed opah, a very ingenious no scientific internal heating system had yet seen in any other species.

A wonderful network

It is by studying closely the gills of a specimen caught off the coast of California that researchers have discovered the secret of the first fish ever identified warm blood. “I immediately noticed that there was something unique,” says Nicholas Wegner, the lead author of the discovery has just been published in the renowned journal Science . In general, in the gills, blood circulation of fish is limited to a few large vessels that carry blood to and from the area. However, in the case of kingfish-moon, its gills were irrigated rather by a complex network of arteries and veins intimately blended, known as “ rete mirabile ” (from Latin, network wonderful) and can serve as a heat exchanger. Everything is wrapped in a relatively thick layer of fat, the insulating properties. Could the salmon gods join the club of warm-blooded animals (or endothermic) whose fish have been excluded? For if tuna, marlin and some sharks are able to heat parts of their body, they are reaching out for a short time, after which they must always return to warmer waters.

Comparative Advantage

To test their hunch, the researchers therefore temperature sensors installed on Moon kingfish swimming in more or less cold waters. Results: even in water at 4 degrees, all of these fish muscles (including the heart) continued to show from 13 to 14 degrees, as his eyes or his brain. What provide the animal sacred comparative advantage in the cold waters it inhabits (between 50 and 200 meters deep). Thus, compared to other deepwater fish slow metabolism, forced to use tricks to achieve food, salmon gods, physically and cerebrally faster more alert, has to figure formidable predator. But how he manages to regulate its body temperature? It beats the pectoral fins! This movement generates heat which heats the blood circulating in the network of vessels that surround the veins of the fish at the rete mirabile of its gills. Thus, his ships and the heat they give off warm in turn oxygenated blood from the veins again towards the internal organs of the animal, thus maintaining their temperature.