The viperwolf (Nantang in Navi) is a hexapodal nocturnal carnivore. The species is scientifically known as Caniferratus costatus. It has bioluminescence for pack identification. Cameron described the viperwolves: "[They are] hairless with shiny skin that looks like overlapped armor. Most disturbing are its paws, which are like leathery hands." They are vicious in combat but treat their babies in a loving, nurturing way. Their first appearance is when Jake is lost at night and he is attacked by an angry pack of viper wolves, after which he is rescued by Neytiri. They are seen in the daytime caring for their babies and have green eyes. They have a laugh which sounds like Earths hyenas. Like most Pandoran creatures, they have antennae. They have opposable thumbs allowing them to climb trees as well as stalk from the ground, thereby are able to create a three-dimensional hunting field.