Over decades of studying the oceans' fishes, some species have been found to have partial warm-bloodedness. But scientists say the opah, or moonfish, circulates heated blood — and puts it to a competitive advantage. "Nature has a way of surprising us with clever strategies where you least expect them," according to NOAA Fisheries biologist Nicholas Wegner, who works in the Southwest Fisheries Science Center in La Jolla, Calif. In a news release about the finding, Wegner said, "It's hard to stay warm when you're surrounded by cold water but the opah has figured it out." The opah is not a...