The mangrove rivulus, a type of fish found from Florida to Brazil, has shown scientists the first example of a fish jumping out of water to cool itself on land, according to National Geographic. That in itself is a pretty cool find, given the rarity of finding any fish that can jump out of water whenever it wants.
But there is one thing about this fish that left researchers wondering what was up. And that involved the conditions of when it escapes water. Where the fish lives in tropical conditions, water temperatures can reach up to 100 degrees Fahrenheit — but the air is not that much cooler. So the question was: Why does this fish jump out of hot water just to bask in hot, humid air?
To find out, researchers simulated its natural environment and observed its behavior when it jumped out of water and onto a sheet of paper. At 97 degrees Fahrenheit, the fish jumped onto the piece of paper. Within 30 seconds, scientists say its temperature equaled that of the air. By 60 seconds, researchers found the fish had become cooler than the paper.
Other fish have been suspected to be able to do similar quick-cooling, scientists say, but none have actually been captured doing it before.
“These fish always have this escape route,” said Patricia Wright of the University of Guelph in Ontario, Canada, to National Geographic. “If the water starts to warm up, off they go.”