Range of Penguins, all species (aqua)
Penguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage and their wings have evolved into flippers. Most penguins feed on krill, fish, squid and other forms of sealife caught while swimming underwater. They spend about half of their lives on land and half in the oceans. Although all penguin species are native to the southern hemisphere, they are not found only in cold climates, such as Antarctica. In fact, only a few species of penguin live so far south. Several species are found in the temperate zone and one species, the Galápagos Penguin, lives near the equator.
The largest living species is the Emperor Penguin, on average adults are about 1.1 m (3 ft 7 in) tall and weigh 35 kg (75 lb) or more. The smallest penguin species is the Little Blue Penguin, also known as the Fairy Penguin, which stands around 40 cm tall (16 in) and weighs 1 kg (2.2 lb). Among extant penguins, larger penguins inhabit colder regions, while smaller penguins are generally found in temperate or even tropical climates. Some prehistoric species attained enormous sizes, becoming as tall or as heavy as an adult human. These were not restricted to Antarctic regions; subantarctic regions harbour high diversity, and at least one giant penguin occurred in a region not quite 2,000 km south of the equator 35 mya, in a climate decidedly warmer.
The word "Penguin" first appears in the 16th century as a synonym for Great Auk. It may be derived from the Welsh pen gwyn "white head", although the etymology is debated. When European explorers discovered what are today known as penguins in the Southern Hemisphere, they noticed their similar appearance to the Great Auk of the northern hemisphere, and named them after this bird, although they are not related. The etymology of the word "penguin" is still debated. The English word is not apparently of French, nor of Brition or Spanish origin, but first appears in English or Dutch.
Some dictionaries suggest a derivation from Welsh pen, "head" and gwyn, "white", including the Oxford English Dictionary, the American Heritage Dictionary,] the Century Dictionary and Merriam-Webster on the basis that the name was originally applied to the great auk, either because it was found on White Head Island in Newfoundland, or because it had white circles around its eyes. An alternative etymology links the word to Latin pinguis which means "fat". In Dutch the alternative word for penguin is 'fat-goose' and would indicate this bird received its name from its appearance.