Southern specialists once named for a northern auk
Penguins are flightless seabirds that live almost entirely south of the equator, with only the Galápagos penguin reaching slightly north of it. They range from emperors about 1.1 metres tall and 35 kilograms down to little blue penguins barely a third of a metre high.
Built for the sea, penguins wear dark backs and pale fronts that camouflage them from above and below, and swim with stiff flippers. Most catch krill, fish and squid in their bills and swallow them whole underwater, gripping slippery prey with a spiny tongue and strong jaws. Larger species tend to live in colder waters and smaller ones in temperate or tropical seas. The International Ornithologists’ Union recognises eighteen species in six genera.
The name was borrowed. In the late sixteenth century penguin meant the great auk of the North Atlantic, and sailors later applied it to southern birds that looked similar, though the two are unrelated. The great auk, extinct by the mid-nineteenth century, belongs with the auks, while Charles Lucien Bonaparte placed true penguins in their own family in 1831, naming it after a Greek word for wedge describing the African penguin’s flippers. Where penguin itself comes from is disputed: some dictionaries point to Welsh for white head, others to Latin pinguis, meaning fat.
The oldest fossils, from New Zealand’s Waipara Greensand, are roughly 62.5 to 58 million years old. Those early birds were already flightless, with short wings for diving, though they paddled mainly with their feet at the surface. By about 42 million years ago penguins lived in Peru, and during the late Eocene and early Oligocene giants flourished: one species stood nearly 1.8 metres and another probably topped 80 kilograms. Around ten species once shared Seymour Island in Antarctica.
The giants were gone by roughly 25 million years ago, a decline that matched the spread of early fish-eating toothed whales competing for the same food. Among living penguins, the emperor’s genus, Aptenodytes, branched off first; they balance their eggs on their feet. The banded penguins and little blues, the only burrow nesters, spread east on the Antarctic Circumpolar Current from about 28 million years ago.
Source: Penguin
