Penguins catch their food while swimming in the ocean. Penguins primarily eat fish, squid and krill that they catch with their sharp beaks. Over their evolutionary history, the ancestors of modern penguins lost their ability to fly in exchange for becoming extraordinary swimmers.
Penguins are among the most skilled fish-eating animals in the world, which is necessary to fuel their high caloric needs. In contrast to fish who need relatively few calories to drive their cold-blooded metabolisms, penguins must eat a lot to heat their bodies internally. Penguins' maneuverability in the water has come at the cost of not only flight, but also gracefulness while walking. Some species engage in a practice called “tobogganing” in which they lie on their bellies and slide from place to place.
There are 17 species of penguins in the family Spheniscidae. While the various species exhibit a great deal of variation, all of them live alongside the oceans and seas of the Southern Hemisphere. Most penguins form very large groups that may contain thousands of individuals. However, penguins are monogamous animals that bond strongly with another individual. Many species have evolved elaborate mating rituals or displays to help individuals stand out from the crowd.