The lizards have tails ringed with rows of sharp, curved spines, hence the name spiny-tailed iguana. The spines down the back are short. The ctenosaur is generally herbivorous, particularly on legume fruits, but is also known to have a diverse carnivorous diet that consist of small animals. Ctenosaurs have eaten rodents, bats, frogs, small birds, and a variety of insects. They have even been noted to eat eggs of their own young, and in one case, the tail of a juvenile was found inside an adult male, suggesting cannibalism.
Youngsters are primarily insectivorous, switching into herbivorous habits as adults.
This species becomes sexually mature at around 3 or 4 years of age. They congregate and mate during specific times of year that varies between populations. Male iguanas possess a pair of intromittent organs, the hemipenes. When not in use the hemipenes lie adjacent to the cloaca within the base of the tail. During sexual activity one hemipenes is everted by the action of muscles and fills with blood.