SEATTLE — The fish buyer noticed something different about the large, colorful disc-shaped opah waiting to be sold at the auction house in Honolulu. Among the differences: one fish had a bigger eye than the other.
His curiosity set in motion DNA testing and more sleuthing that led to the identification of three new species of opah — a peculiar deep-diving fish recently found to be the first fully warm-blooded fish.
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“The more we looked, the more differences we could pull out,” said Karen Underkoffler, lead author of a recently published paper in the peer-reviewed journal Zootaxa that describes the anatomical characteristics of the different species of opah, including one marked by its big eyes and a purple tongue.
In all, the team of scientists with NOAA Fisheries identified five distinct species of opah, revealing that there isn’t a single global species. Three are newly identified, one was already named and researchers better identified another that had been previously described.