Gorillas are a large species of primate that live in a few small portions of Africa. There are four different subspecies, and all are considered endangered. The western lowland gorilla has the largest population at up to 200,000 individuals in the wild, while the river gorilla subspecies only has approximately 300 individuals.
There is a significant difference in size between male and female gorillas. Males can grow up to 5.5 feet tall and weigh up to 450 pounds, while females usually only reach 5 feet and 200 pounds. Gorillas have an average lifespan of between 30 and 50 years, and they are herbivores who eat leaves, fruits and vines.
Male gorillas go through a significant change in color during their lives. From ages 8 to 12, they have mostly black fur and are called "blackbacks". The more visible silver color, which earns male gorillas the name "silverback," doesn't occur until they are at least 12 to 15 years old.
All gorillas have an opposable big toe that gives them added control over the items with which they interact. This toe moves in much the same way as the human thumb. They also have opposable thumbs on their hands, and babies use these opposable digits to grip their mother's fur so that they can travel with her without hampering the mother's use of her arms.