The strange looking opah (Lampris guttatus), one of the tastiest fish in the sea, has another thing going for it that no other fish has. It is warm blooded. That’s right the opah, shaped like a big flat orb with orange fins and white spots, keeps its body warm, according to scientists with the National Oceanic and Atmospheric Administration.
The scientists found that the opah constantly flaps its fins to generate enough heat to warm its body, making it a more efficient predator.
NOAA Fisheries biologist Nick Wegner holds an opah caught during a research survey off the California Coast. Photo by NOAA Fisheries/Southwest Fisheries Science Center
The fish has blood vessels in its gills that carry warm blood into the gills and are wrapped around blood vessels that carry cold blood back to the body’s core. This design is known in engineering circles as counter-current heat exchange. Acting similar to a car radiator, the opah’s warm blood heats the body’s core as cold blood returns from the surface of the gills where oxygen is absorbed. The opah also has fatty tissue around their gills, heart and muscles that keep their body temperature warmer than the surrounding water.
“Before this discovery I was under the impression this was a slow-moving fish, like most other fish in cold environments,” NOAA biologist Nicholas Wegner said in a statement. “But because it can warm its body, it turns out to be a very active predator that chases down agile prey like squid and can migrate long distances.
So chalk this up as an interesting scientific discovery. While bluefin tuna have been known to maintain body temperatures of up to 11 degrees warmer than the surrounding waters, it doesn’t occur all the time. Who would’ve known that a fish could be fully warm blooded?