Opah is a voracious predator.
By Raif Karerat
WASHINGTON, DC: Membership in the animal kingdom’s warm-blooded club just got a little more diversified after a fish called the Opah became the first of its kind to earn the recognition.
Researchers announced in the journal Science that the Opah is the first denizen of the deep waters to classify as fully warm-blooded in that it circulates heated blood throughout the entirety of its body.
The Opah’s adaptation, unique among fish as far as science is aware of thus far, enables it to function as a voracious predator in the sub-zero depths of the ocean.
According to Reuters, Tuna and certain sharks are able to warm specific regions of their body while hunting in the frigid deep, such as their swimming muscles, brain, and eyes, but must return to the surface in order to safeguard the functionality of certain organs such as the heart.
Instead of making repeated trips to the surface, where the risk of becoming a meal for a larger predator would assumedly increase, the Opah generates internal heat by constantly flapping its wing-like pectoral fins. In doing so, the Opah’s average muscle temperature is maintained at about 7 degrees to 9 degrees Fahrenheit (4-5 degrees Celsius) above the surrounding water temperature at any given time.
A structure unique to the Opah, colloquially known as the moonfish, lets warm blood that leaves the body core help heat up the cold blood that’s recently passed through its gills, said fisheries biologist Owyn Snodgrass of NOAA and Ocean Associates Inc. In most fish, the heat in their blood is immediately lost since it has to effectively come into contact with ocean water within the gills.
The Opah’s warm blooded nature lends it distinct advantages over its cold-blooded prey and competitors, including faster swimming speeds and reaction times, and better eye and brain function, reported NBC News. Fish that survive at such crushing depths are typically are slow and sluggish, with predators resorting to ambushing rather than pursuing prey.
The Opah (Lampris gutattus, according to The Guardian) is a burnt reddish color with white spots and bright red fins. It can weigh up to 200 pounds (90 kg) and is about the size of a car tire, with an flat, oval body shape. Found throughout all of the world’s oceans, it spends most of its time at depths of 165-1,300 feet (50-400 meters) hunting squid and other fish.