What are penguins’ modified wings commonly called?

Penguins’ modified wings are commonly called flippers.

Unlike the broad, flexible wings of most flying birds, a penguin’s flippers are short, stiff, and flattened. Dense bones and strong muscles help them function as underwater propellers. Penguins use them to generate thrust while their streamlined bodies reduce drag, allowing controlled movement through the sea.

Penguin flippers are adapted for swimming rather than flight. The birds cannot lift their heavy bodies into the air, but several species can travel quickly underwater and make powerful leaps out of the water. Their legs and webbed feet mainly help with steering, braking, and movement on land or ice.

A penguin’s flipper is not the same as a seal’s flipper, although both structures serve aquatic purposes. Penguins remain birds: they have feathers, beaks, lungs, and wings. Their unusual wing design is a classic example of evolutionary specialization for marine life.