Skag

Skags are large, dog-like creatures, easily identified by their strong bony armor plates, aggressive behavior, and distinctive three-jawed mouths.Skags dwell in underground burrows. Though skags primarily carve out their burrows by using their hard, hook-like claws to dig, the molded appearance of their den entrances evidences the use of corrosive compounds - common to some types of skag - to break down the Pandoran stone. Skags seem to behave like meerkats, with most of the pack inside the den and a few roaming just outside. Skags' distinctive mouths consist of a relatively immobile lower jaw supporting two vertically aligned upper jaws which, when opened, seemingly cause the face to split. Despite the ferocious appearance of their mouths, skags do not appear to have teeth. Instead, a series of barbs extends from the end of their lower jaw and along both edges of their upper jaws. This suggests that skags might ingest prey in the same manner as alligators on Earth - by ripping apart the flesh rather than biting it in chunks.  Skags' tongues grow with age. When at the 'elder' stage of maturity and fully extended, this strong, potentially prehensile organ may be up to twice as long as the body.Skags are armored brutes that typically attack in groups of 3-6 individuals mobbing their prey. They are moderately tough, and all breeds sport appreciably armored areas around their head, shoulders, and along their back. The armor on these sections is thick enough to cause some trouble - even the weakest skag pup will take only half damage when shot in the head or shoulder as opposed to the gut, causing you to waste ammo while more skags crawl out of their dens. Fortunately, skags have a weak spot - their open mouths can be exploited when they stop and roar.