A normally aquatic species raised on land suggests how ancient fish might have transitioned into terrestrial species
The deft wrigglings of fish forced to grow up on land could offer a glimpse of how ancient vertebrates started to make the big move out of the sea.
The modern fish species called Senegal bichir (Polypterus senegalus) normally swims in African rivers. But the elongated fish possesses both gills and lungs and can walk on land if it has to. And that’s what Emily Standen forced bichirs to do for much of their youth.
While working at McGill University in Montreal, she created tanks with special bottoms that let only a few millimeters of water seep across the surface where the fish would move. Grocery-store produce aisles provided additional inspiration for the tanks’ design. (“We need misters, lettuce misters!” she realized.) For eight months, the tanks housed crowds of roughly 7- to 8-centimeter-long young fish, which used their fins and tails to dart around the bottom looking for food.