There are a number of animals that can't walk backwards, including but not limited to: chickens, penguins, turkeys, emus and ostriches. The main reason these animals can't walk backwards is because of their anatomy; they simply don't have the skeletal structure or muscular strength to support them. Chickens, for example, have an overdeveloped breastbone that makes it very difficult for them to move their legs in a backward motion. Penguins have flipper-like wings that make it impossible for them to get any traction if they tried to walk backwards. Turkeys have incredibly long legs in proportion to their bodies which also makes it difficult for them maneuver in a backward direction. Emus and ostriches are both flightless birds with two toes on each foot instead of the usual four found on most land-dwelling animals; this makes it hard for them to keep balance while moving backwards.