Fish raised on land use fins to walk

By Casey Frye, CCNN Writer

fish evolution
Millions of years ago, fish slowly evolved to survive on land.

In an environmental adaptation process known as evolution, living creatures transform their bodies and behavior to better survive their surroundings. Over 400 million years ago, fish fins slowly evolved into wiggly legs, enabling the creatures to venture out from the ocean onto land. Now, scientists have recreated this process by raising fish in land-like conditions, and the critters actually changed the way they walk!

“I used to look at fins and their motion, and I always thought it was so interesting and complex,” explained Emily Standen, the lead author of the study. “And then I thought, wow, how does that change from a fin to something that might work on land? That’s how this project started.”

With that mission in mind, scientists experimented on 111 juvenile (young) Polypterus senegalus, a fish species commonly called “dinosaur eels”. While 38 of them were raised in a normal watery environment, the rest were forced to survive in 3 millimeters of pebble-filled water. The dinosaur eels who lived in the terrestrial (earthly) setting were also sprayed with watery mist to make sure they didn’t end up dried out.

After 8 months, the Polypterus senegalus in the drier environment started moving differently to better navigate their surroundings! “Fish raised on land walk with a more effective gait,” said Standen. “They plant their legs closer to the body’s midline, they lift their heads higher, and they slip less during that walking cycle.” That’s not all, either, because the dinosaur eels physically morphed! The bones that support the fins changed shape and their collarbones grew longer, to help their heads and fins move better.

Featured image courtesy of Antoine Morin on Nature. Image of fish evolution courtesy of Maija Karala on Wikipedia.