As kids we were taught that fish, reptile and amphibians are cold-blooded, and birds and mammals are warm-blooded.

Simple, easy classification.

Think again.

Researchers have found the first fish that is fully warm-blooded. A silvery fish the size of a car tire, the opah has a worldwide distribution.

Read the article about how it warms its little fishy body over at Science! Or at the New York Times!