How do you know a penguin is a flightless bird?

Answer 1

Penguins are a group of aquatic, Flightless Birds living almost exclusively in the Southern Hemisphere. Penguins are superbly adapted to an aquatic life. Their wings have become flippers, useless for flight in the air. In the water, however, penguins are astonishingly agile.

Most penguins feed on krill, fish, squid, and other forms of sea life caught while swimming underwater. They spend half of their life on land and half in the oceans.

Penguins seem to have no special fear of humans and have approached groups of explorers without hesitation. This is probably on account of there being no land predators in Antarctica or the nearby offshore islands that prey on or attack penguins.