Penguins (order Sphenisciformes, family Spheniscidae) 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 become 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 (Aptenodytes forsteri): 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 (Eudyptula minor), 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 (see also Bergmann's Rule). Some prehistoric species attained enormous sizes, becoming as tall or as heavy as an adult human. These were not restricted to Antarctic regions; on the contrary, subantarctic regions harboured 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 than today.

Paul Nicklen (born July 21, 1968, Tisdale, Saskatchewan) is a Canadian biologist and photographer.

Paul Nicklen was born in Saskatchewan Province but grew up in an Inuit community on Baffin Island in the Canadian Arctic.

He received a Bachelor of Science degree in marine biology from the University of Victoria, British Columbia, in 1990. After University, he worked in the Northwest Territories as a wildlife biologist with Canada's Department of Renewable Resources. He studied species such as lynx, grizzly bears, bison, caribou and polar bears as a biologist before becoming a wildlife and nature photojournalist in 1995.

Since 1995, Nicklen has worked as a full time photojournalist specializing in the Arctic and Antarctica with an emphasis on wildlife and climate change.

Paul Nicklen is a contributor photographer for National Geographic Magazine. He is a Fellow of the International League of Conservation Photographers (ILCP).

Major exhibits of his work include Extreme Exposure at the Annenberg Space for Photography in Los Angeles, California [16].