As much as we want to believe we’ve seen everything under the sun, there’s still a world in the ocean that remains to be fully discovered. Despite our sophisticated, deep-diving technologies, scientists are still finding new species and underwater life forms.
Case in point: the opah (Lampris guttatus), the first warm-blooded fish ever discovered. Until now, fish have always been thought of as ectothermic, meaning that they require heat from their surrounding environment to stay warm.
The opah is a large, orange and spotted moon-shaped fish about the size of a car tire. Scientists suspected its warm-bloodedness when researching its gill tissue when they discovered that vessels carrying cold, oxygenated blood were in contact with vessels carrying warm, deoxygenated blood from the body tot the gills. Therefore, outgoing blood warms the incoming blood.
The fish’s warm blood gives it an advantage for hunting prey. Many cold-blooded fish (like tuna) can push blood to various parts of the body to keep warm during deep dives, but they have to resurface frequently to keep organs from shutting down. The opah’s bloodstream, in contrast, gives them a heightened nervous system and enables them to stay underwater longer. Who knows what the next undersea discovery will reveal!