The number of penguin species has been and still is a matter of debate. The numbers of penguin species listed in the literature varies between 16 and 19 species.
Some sources consider the White-flippered Penguin a separate Eudyptula species, while others treat it as a subspecies of the Little Penguin (e.g. Williams, 1995; Davis & Renner, 2003); the actual situation seems to be more complicated (Banks et al. 2002). Similarly, it is still unclear whether the Royal Penguin is merely a color morph of the Macaroni penguin.
Also possibly eligible to be treated as a separate species is the Northern population of Rockhopper penguins (Davis & Renner, 2003). Although all penguin species are native to the southern hemisphere, they are not, contrary to popular belief, found only in cold climates, such as Antarctica. In fact, only a few species of penguin actually live so far south. Three species live in the tropics; one lives as far north as the Galápagos Islands (the Galápagos Penguin).
The largest living species is the Emperor Penguin (Aptenodytes forsteri): adults average 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). Generally larger penguins retain heat better, and thus inhabit colder regions, while smaller penguins are found in temperate or even tropical climates (see also Bergmann’s Rule). Some prehistoric species attained enormous sizes, becoming as high as an adult human; see below for more.
Most penguins feed on krill, fish, squid, and other forms of sealife caught while swimming underwater. They spend half of their life on land and half in the oceans.
When mothers lose a chick, they sometimes attempt to steal another mother’s chick, usually unsuccessfully as other females in the vicinity assist the defending mother in keeping her chick.
Penguins seem to have no fear of humans and have approached groups of explorers without hesitation. This is probably on account of there being no land predators in Antarctica or the nearby offshore islands that prey on or attack penguins. Instead, penguins are at risk at sea from predators such as the leopard seal. More..
Adults average about 1.20 metres (4 ft) and weigh 30 kilograms (75 lb) or more. The largest known individual was about 46 kg. The head and wings are black, the abdomen white, back bluish grey, and the bill is purplish pink. On the sides of the neck, there are two golden circular stripes. Like the King Penguin counterpart, a male Emperor Penguin has an abdominal fold, the “brood pouch”, between its legs and lower abdomen.
The Emperor penguin has a thick coat of feathers that insulate the entire body, excluding only the legs and the undersides of the wings. The feathers provide a waterproof layer around the penguin’s body.
Emperor penguin chicks are covered with a thick layer of light gray down. This covering ensures that they retain as much heat as possible, vital at this early stage when they are not capable of maintaining their body temperature. In addition, the infant emperor penguin’s orbital area is covered in white downy feathers, unlike the all-black feathered head of the adult.
A distinguishing characteristic between males and females is their call. Each call is distinct. They also are related to the King and the chinstrap penguin. More..