Most birds changed their bodies to make flying possible through *evolution.
Now, they have *wings instead of arms. Their *bones are lighter than the bones of
other animals. Because of the unique power of flying in the sky, they have had
more chances to get away from their enemies. and to find enough food. So, they
have *survived in this world.
However, some birds lost this unique power and took different ways of evolution.
Penguins are good examples. There are 18 kinds of penguins on the Earth, and
most of them live along the sea in the south part of the Earth. They are loved
around the world. Their round body with small wings looks cute. Their walking
