This car-tire-size opah (Lampris guttatus
) is not your usual fish- it’s got warm blood. This rotund, silver bodied creature is an endotherm which means its own temperature elevated even as it dives to chilly depths of 1,300 feet (396 meters) of the ocean.
"Increased temperature speeds up physiological processes within the body," study leader Nicholas Wegner, a biologist at the National Oceanic and Atmospheric Administration (NOAA) Fisheries' Southwest Fisheries Science Center in La Jolla, California, told Live Science. "As a result, the muscles can contract faster, the temporal resolution of the eye is increased, and neurological transmissions are sped up. This results in faster swimming speeds, better vision and faster response times."
Also known as the moonfish, it has relatively small red fins which can grow up to 6 feet (1.8 meters) long. "The opah appears to produce the majority of its heat by constantly flapping its pectoral fins which are used in continuous swimming," Wegner said.
Aside from this, after analyzing a sample of the fish's gill tissue, researchers found that blood vessels from the gills allow outgoing blood to warm up the incoming blood. "There has never been anything like this seen in a fish's gills before," Wegner said in a statement. "This is a cool innovation by these animals that gives them a competitive edge. The concept of counter-current heat exchange was invented in fish long before [humans] thought of it." Moreover, fat deposits around the gills and muscles are also found to help insulate the fish.
This deep-sea dweller was then tracked down further only to know that they can actually have a constant body temperature that stays about 9 degrees Fahrenheit (5 degrees Celsius), warmer than the surrounding water, no matter how deep they dive! This means that unlike tuna and some sharks, it needs not to swim up to survive- it can really stay deep for long periods of time.
"Nature has a way of surprising us with clever strategies where you least expect them," Wegner said in a statement. "It's hard to stay warm when you're surrounded by cold water, but the opah has figured it out."
Now, can you imagine eating a warm-blooded fish like this? This is actually available in the menu of some restaurants all around the world. Well, I wonder how it tastes like.