This opah was caught during an NOAA Fisheries survey off the California coast. (Credit: NOAA Fisheries/Southwest Fisheries Science Center) All fish are cold-blooded. Just a week ago, that statement would have been true. But on Thursday, scientists announced they discovered the world’s first warm-blooded fish, the opah, forcing us to rethink some of the most basic biological concepts we learned back in elementary school.
Opah, also known as moonfish, are rotund — almost comically so — predatory fish that hunt for prey in cold, dark waters up to 1,000 feet below the ocean’s surface. Although they aren’t fished commercially, opah are often accidentally caught in fishing nets. Hawaiians consider opah a sign of good luck, and the fish are often given away as a gesture of goodwill. But opah have long intrigued scientists because they are such nimble hunters in deep water; most predatory fish move slowly at these depths ...
