The Chinchilla is a rodent that looks like a cross between a squirrel and a rabbit. A little larger than a guinea pig, the average weight of a chinchilla is between 1 and 4 pounds. In captivity, their life expectancy is around 10 to 20 years. In the wild, the lifespan is in the range of 10 to 15 years. As herbivores, their diet consists of grasses, berries, and plants.