Penguin.

      

          Penguins are aquatic, flightless birds that are highly adapted to life in the water. They live almost exclusively in the Southern Hemisphere, where they catch their food underwater and raise their young on land. Penguins' distinct tuxedo-like appearance is called countershading, a form of camouflage that helps them safe in the water. The penguin species with the highest population is the Macaroni penguin and the lowest population is the endangered Galapagos penguin. Penguins eat seafood. Their main diet is fish, though they will also eat squid, small shrimplike animals like krill. 

          Penguins are social birds. Many species feed, swim and nest in groups. During the breeding season, some species form large groups, or "rookeries", that include thousands of penguins. Each penguin has a distinct call, allowing individuals to find their mate and chicks even in large group. Here is a video about penguins' breeding life.

         Here are some fast facts about penguins :- 

• Size : The blue penguin, also known as the fairy penguin, is the smallest of the penguin species at 16 inches tall and weighs about 2.21 pounds. The largest penguin species is the emperor penguin, which is about 3.7 feet tall and weighs between 60-90 pounds.

• Lifespan : 15-20 years depending on the species.
• Gentoo Penguin is the fastest species which can reach swimming speeds up to 22 mph.
• The closest relatives to penguins are petrels, albatrosses and divers.