Penguins are birds, and like other birds, they have wings and are covered with feathers. They lay eggs and are warm-blooded animals.

Penguins evolved from the flying birds of more than 40 million years ago. The first penguin fossil fragments were found in New Zealand in the mid-1800s. To date, the discovery of all penguin fossil fragments has been limited to the Southern Hemisphere. The closest living relatives to penguins are the albatrosses, shearwaters, petrels, loons and grebes.

The origin of the word penguin has been a subject of debate. Theories range from references to the amount of fat penguins possesses (penguigo in Spanish and pinguis in Latin) to the claim that the word was derived from two Welsh words meaning “white head.” The most agreed-upon explanation is that penguin was used as a name for the now-extinct great auk, which the modern-day penguin resembles and for which it was mistaken.

Scientific classification

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Aves
  • Order: Sphenisciformes
  • Family: Spheniscidae
  • Genera: Aptenodytes, Eudyptes, Eudyptula, Megadyptes, Pygoscelis, Spheniscus

Distribution and habitat

All 18 species of penguins live in the Southern Hemisphere. Penguins generally live on islands and remote continental regions that are free of land predators, where their inability to fly is not detrimental to their survival. Penguin species are found on every continent in the Southern Hemisphere. They are abundant on many temperate and sub-Antarctic islands. Different species thrive in varying climates, ranging from Galapagos penguins on tropical islands at the equator to emperor penguins restricted to the ice of

These highly specialized marine birds are adapted to living at sea. Some penguin species spend as much as 80% of their lives in the ocean. They usually are found near nutrientrich, cold-water currents that provide an abundant supply of food.


Penguins only eat seafood and swallow their food whole since they don’t have teeth. They use their powerful, sharp beaks to catch fishes, squid and krill. Their tongues have a rough, Velcro-like texture that—along with a hooked beak—helps them hold and swallow their slippery food. The New England Aquarium’s penguins eat nearly 600 pounds of sardine, capelin, smelt and herring every month. Most of them eat five to ten fishes every day.

Physical characteristics

There are 18 different species of penguins, and they vary in size and shape. The emperor penguin is the largest of all living penguins, standing at 4 feet and weighing 90 pounds. The smallest of the penguins is the little blue penguin, standing just 10 inches and weighing about 2.5 pounds. Everything about a penguin is fine-tuned for swimming.


Male and female penguins look alike, even to the trained eye. Observing mating behavior, performing an internal examination, or doing DNA analysis are the only ways to distinguish male from female penguins. The reproductive behaviors such as mating, courtship and nesting differ from species to species. The color, shape and size of eggs also differ.

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