Today 20-foot crocodiles are very rare, but some of them are still out there in the wild, with a few held in captivity. Renowned herpetologist Romulus Whitaker attempts to ensure the future of the last of these leviathans.

NATURE interviews Romulus Whitaker, the reptile expert and conservationist featured in "The Dragon Chronicles."

The crocodile has few natural predators, an armor of bony plates covering most of its body and strong jaws capable of crushing anything from bones to cast iron.

Conservationist Rom Whitaker searches for the last of the supersize crocodiles among the titans of the croc world: Nile crocodiles, saltwater crocodiles, and gharials.

To leap straight out of the water, the crocodiles use power from their tails, which have ball-and-socket joints between the vertebrae for maximum motion.

Crocodiles are too dangerous to approach with a tape measure. Rom Whitaker and an assistant use photography to make an estimation of a gharial's size.

Explore this interactive feature to learn about different aspects of the crocodile's anatomy.

The Nile crocodile is known for its incredible ambush power. This amazing footage shows the crocodile nabbing its prey from the banks of the Grumeti River.

View additional resources, online and in-print, for NATURE's "The Dragon Chronicles."