 Both males and females grow to an adult length of from snout to vent, with a total length of , making them the third-largest aquatic salamander species in the world (after the Chinese giant salamander and the Japanese giant salamander, respectively) and the largest amphibian in North America, although this length is rivaled by the reticulated siren of the southeastern United States (although the siren is much leaner in build).An adult weighs , making them the fourth heaviest living amphibian in the world after their Chinese and Japanese cousins and the goliath frog, while the largest cane toads may also weigh as much as a hellbender.Hellbenders reach sexual maturity at about five years of age, and may live 30 years in captivity.