WHY PENGUINS CANNOT FLY

In one sense, it could be stated that penguins do fly. It's just that they fly underwater, rather than in the air.


There are a number of reasons why penguins do not fly in the air.


Penguins eat fish. The fish they eat swim fairly deep under water, so flying is not an advantage in getting the fish, but swimming is. Therefore, penguins swim rather than fly. Quite simply, they don't fly because they don't need to.


Penguins cannot fly in air because their wings are too small for their body weight. Power required to stay aloft to counteract gravity is proportional to wingspan. Penguins have very small wings, yet are very heavy. The heaviest penguins are heavier than the heaviest flying birds. The heavier bodies of penguins are the result of their special bone structure and the blubber that they carry.


Their wing bones are fused straight, rather than angled like a flying bird's, and this has the effect of making the wing rigid and powerful, like a flipper. The small wings and a streamlined body shape are ideal for diving in water. Larger wings would create too much drag, while the small penguin wings are excellent for high speed swimming.


Unlike the majority of other birds, penguins do not have hollow bones, so are much heavier and harder to support with their small wings. The solid, as opposed to hollow, bones act as ballast to help them dive. Also, being solid, they are less prone to breakage from the stresses of swimming. Some (but not all) flying birds have hollow bones to be lighter.


Of all animals, birds are perhaps best known for their ability to fly, but many kinds of birds are flightless. Penguins belong to a group called Sphenisciformes, in which all species are flightless and aquatic. Another group of flightless birds is known as the ratites. It includes the ostriches of Africa, rheas of South America, emus of Australia, cassowaries of New Guinea and Australia, moas (now extinct) and kiwis in Australia, and elephant birds of Madagascar (an extinct group that includes the largest birds ever known). Other flightless birds include a species of cormorant in the Galapagos, a grebe in the Andes, a parrot in New Zealand, and several species of pigeons on islands in the South Pacific and Indian Oceans.


The anatomy and brain structure of flightless birds indicate that they all descended from ancestors that could fly. In many cases, flightless birds inhabit islands where there are no predators. Without the energetically costly need to take flight from predators, many of these birds have become more specialized for a lifestyle on the ground or in the water and completely lost their ability to fly.




Penguins have some of the same characteristics of many diving birds, but they have evolved additional features that reflect their highly aquatic lifestyle, such as the reduction and fusion of the wing bones into paddle-like flippers. Also, rather than having hollow bones as flying birds do, penguins have solid heavy bones that function as ballast (weight) for more efficient diving. Furthermore, penguins actually use their wings for moving under water much like any other bird does to move through the air; such that many people remark that penguins appear to be "flying" through the water.