Despite its taxonomic classification as a carnivore, the giant panda’s diet is primarily herbivorous, consisting almost exclusively of bamboo. However, the giant panda still has the digestive system of a carnivore, as well as carnivore-specific genes, so a diet of strictly bamboo gives the bear little energy and little protein. Because bamboo is so low in nutrition, pandas spend at least 12 hours each day eating and must keep their digestive tract full. Pandas eat as much as 84 pounds (38 kilograms) of it each day. The limited energy input imposed on it by its diet has also affected the panda’s behavior. The giant panda tends to limit its social interactions and lives a relatively sedentary life to limit its energy expenditures.
Pandas grasp bamboo stalks with their five fingers and a special wristbone, then use their teeth to peel off the tough outer layers to reveal the soft inner tissue. Bamboo leaves are also on the menu, as pandas strip them off the stalks, wad them up, and swallow them.
Two of the panda’s most distinctive features, its large size and round face, are adaptations to its bamboo diet. Pandas have a low metabolic rate due to their diet. Similarly, the giant panda’s round face is the result of powerful jaw muscles, which attach from the top of the head to the jaw.Large molars crush and grind fibrous plant material.
Pandas eat any of 25 bamboo species in the wild. Only a few bamboo species are widespread at the high altitudes pandas now inhabit. Bamboo leaves contain the highest protein levels; stems have less. Because of the life cycle of bamboo, the giant panda must have at least two different species available in its range to avoid starvation. While primarily herbivorous, the giant panda still retains decidedly ursine teeth, and will eat meat, fish, and eggs when available.
In captivity, zoos and reserves typically maintain the giant panda’s bamboo diet, though some will provide carrots, yams, and special leaf eater biscuits (often called panda cake) made of grain and packed with all the vitamins and minerals pandas need.