The Atlantic puffin (Fratercula arctica) is a bird species that feeds on the North Atlantic Ocean. They dive and, literally, fly in the water: they flap just like if they were flying in the sky. This is how they chase and hunt small fish, the main course on their diet.
They spend Winter in the ocean, far from the dry land, and they come close to it for breeding, in Spring. They nest in cliffs and rocky shores, building the nest in holes on the rocks or digging small galleries on the grass, and lay one single egg.
There is a tiny issue with their food: it is far from the coast, so they would have to fly too many times to bring fish to their offspring. But evolution came up with a solution.
How to take advantage of the trip
Bringing more than one fish each trip they would spare energy and time so, get on with it. They fill the beak with five or six fish and, this way, a single trip provides enough food for a while.
Evolution led them to adapt by reshaping their beak: instead of having a pincer beak, which would only take one fish at a time, they have a hinge joint which allows them to place both halves of the beak parallel to each other. This way, they keep fishing while holding the catches with their tongue, until they have enough to feed the chick. This is the best way to be sparing with the effort of going back and forth to the nest with more food.
Unfortunately, puffin’s populations are disappearing at a worrying rate, as warming seas and oceans lead to the decline of their main food source, the sand eel. Adults try to feed their chick with other kind of fish but is unable to swallow them, so it ends starving to death.