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Brian Skerry, National Geographic

A gentoo penguin (Pygoscelis papua) mother stands with her chick in Antarctica. When walking on land, gentoo penguins waddle with their long tails dragging behind them; but in the water, they are the fastest penguins of them all, reaching swimming speeds of 36 kilometers per hour (around 22 miles per hour).

The penguins breed on islands in the Antarctica, stacking stones to build nests to keep the eggs from rolling away. The males will fight over the best stones to build a nest, and will present the finest stones to females as gifts.