Penguins are seabirds in the family Spheniscidae.  They use their wings to travel underwater, but they cannot travel in the air.  They eat fish and other seafood.  Penguins lay their eggs and raise their babies on land.

Penguins live only in the Southern Hemisphere of the world: Antarctica, New Zealand, Australia, South Africa and South America. The furthest north they get is the Galapagos Islands, where the cold Humboldt Current flows past.

Physical description 
All penguins have a white belly and a dark, mostly black, back.  This is a type of camouflage to keep them safe when they swim, because it makes them blend in with their background. The white and black colors make an effect called countershading. When a predator looking from below sees the white belly and wings of a swimming penguin, they can not see the penguin well because the light is coming from above. However, when seen from above, the penguin's black back blends in with the dark water below, so they are hard to see.

The biggest penguins may stand nearly 4 feet tall (110 cm) and can weigh almost 100 pounds (40 kg). The smallest kinds are only about one foot (32 cm) tall.

Penguins have a thick layer of blubber that helps them keep warm, and their feathers are very tightly packed to make another cover. They also have a layer of woolly down feathers, under the outer veined feathers that are coated with a type of oil that makes them waterproof.

Penguins have webbed feet used for paddling in  the water. They cannot walk well, so they waddle. Penguins cannot fly, but they can swim very well. Their wings have become stiff and small swimming flippers.  They have good hearing and can see underwater.

Life 
Most penguins lay two eggs per year but emperor penguins lay only one. After the penguins mate, the mother lays her egg or eggs and soon goes in the ocean to eat. The father and mother take turns keeping the eggs warm, and the chicks warm after hatching. The parent on baby duty has nothing to eat. Parent penguins call to find each other amongst the thousands of birds when they return from the feeding grounds. The time one parent is alone with the eggs or chicks and going hungry may be weeks or months depending on what kind of penguin they are. If one parent does not return, the other must abandon the egg to go and eat. Global warming is a threat to penguins along with other arctic animals.

Diet 
Penguins eat krill, fish, squid, and other small animals from the ocean, which they catch. They are at home in the ocean. They come up on the land or ice to lay their eggs and raise the chicks. They don't eat there because they live in places where the land has no food for them. In most species the birds all nest together in a huge group, called a rookery.  They usually make nests on the ground with rocks or mud.

Penguins cannot taste fish. This was discovered when a research team noticed they were missing some key genes for taste. A closer look at the DNA of penguins showed that all species lack functioning genes for the receptors of sweet, umami, and bitter tastes. It doesn't matter to them, because they swallow the fish whole.

Different kinds 
There are 15-20 living species (types) of penguins. The white-flippered penguin is today generally considered a subspecies of the little penguin. It is still unclear if the royal penguin is a subspecies of the macaroni penguin.  Scientists are also uncertain whether rockhopper penguins are one, two, or three species.

List of penguins 
 Aptenodytes
 King penguin (Aptenodytes patagonicus)
 Emperor penguin (Aptenodytes forsteri)
 Pygoscoscelis
 Adélie penguin (Pygoscelis adeliae)
 Chinstrap penguin (Pygoscelis Antarctica)
 Gentoo penguin (Pygoscelis papua)
 Eudyptes (crested penguins)
 Rockhopper penguin (Eudyptes chrysocome)
 Fiordland penguin (Eudyptes pachyrhynchus)
 Snares penguin (Eudyptes robustus)
 Royal penguin (Eudyptes schlegeli)
 Erect-crested penguin (Eudyptes sclateri)
 Macaroni penguin (Eudyptes chrysolophus)
 Megadyptes
 Yellow-eyed penguin (Megadyptes antipodes)
 Eudyptula
 Little penguin (Eudyptula minor)
 White-flippered penguin (Eudyptula minor albosignata)
African penguin (Spheniscus demersus)
 Magellanic penguin (Spheniscus magellanicus)
 Humboldt penguin (Spheniscus humboldti)
 Galápagos penguin (Spheniscus mendiculus)

Images

Related pages 
 Tux (Linux mascot)

References

Other websites 

 Penguin at Citizendium

 
Flightless birds
Animals of Antarctica