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There are 7 families of truly Flightless Birds in total. They include the Kiwi, Cassowaries, Rheas, Ostriches, Tinamous, Emus and Penguins.

Some of these belong to the family of birds known as ratites. Ratites include the Southern cassowary of Australia and New Guinea, the emu of Australia, the kiwi from New Zealand, the ostrich from Africa and the rhea from South America.

Ratites have wings but the bones in their chests do not have the capacity for flight muscles, which is what a bird needs to fly. Also, their wings are also too small by comparison to lift them.

Like ratites, penguins are flightless because they have wings which are too small to support their body weight. 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. 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.

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13y ago

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