All are black and white penguins with yellow crests, red bills and eyes, and are found on Subantarctic islands in the world's southern oceans.

[4] The type species was designated as the southern rockhopper penguin by George Robert Gray in 1840.

[5][6] Six extant species have been classically recognised, with the recent splitting of the rockhopper penguin increasing it to seven.

Mitochondrial and nuclear DNA evidence suggests that the crested penguins split from the ancestors of their closest living relative, the yellow-eyed penguin, in the mid-Miocene around 15 million years ago, before splitting into separate species around 8 million years ago in the late Miocene.

British ornithologist David Lack theorized that the genus was evolving toward the laying of a one-egg clutch.

[13] Experiments with egg substitution have shown that A-eggs can produce viable chicks that were only 7% lighter at time of fledging.