At present, there are 18 species of penguins in the world. Characterized by inability to fly; Feet are born in the lowest part of the body, so they are upright; There is webbed toes; Foot flexibility (other birds land on their toes); Forelimbs have fins; Feathers are short to reduce friction and turbulence; There is a layer of air between the feathers for heat insulation. The back is black and the abdomen is white. The main differences between species are head color and individual size.