Flesh

The  is a horribly mutated pig appearing in S.T.A.L.K.E.R.: Lost Alpha and other S.T.A.L.K.E.R. games.

"Like most other living creatures in the Zone, the domestic pig also underwent serious biological changes since the day of the catastrophe. It seems the genes responsible for metabolism were especially affected in this case. Mutant pigs, known simply as Flesh among the stalkers, are one of the most vivid examples of the Zone's disastrous perversion of nature. Mutant pigs developed a protective layer of scales and exoskeletal plates. Their regeneration potential increased several times, as did the complexity of their nervous system. Just like a normal pig, a Flesh is an omnivore and may attack a stalker if hungry."

- Encyclopedia description

Overview
Like many other living creatures, domestic pigs in The Zone underwent serious mutations following the second Chernobyl disaster, affecting genes responsible for their metabolism. This eventually caused the animal's phenotype to change significantly.

Biology
A mutant pig of this type, known as a "Flesh" among stalkers, is one of the clearest examples of the Zone's perversion of nature. The pigs have developed a protective layer of both scales and bones, their regeneration potential grew significantly, and their nervous system became more complex. A side benefit of this mutation is their enlarged eye, which can see in a greater spectrum of light and has olfactory receptors within (in layman's terms, the flesh can smell with its eyes).

They are familial creatures and usually travel the Zone in packs numbering five or six Fleshes. A pack is led by an Alpha Flesh, most often the most experienced and long-lived one. The "Alpha Pig" can be easily identified by both its grayish skin and the scars covering most of its body.

Just like a normal pig, the Flesh is an omnivore and may attack a Stalker if desperate enough. Fleshes have been observed dragging corpses of small slain mutants, such as Blind Dogs, into a safe spot for consumption.

Uses
Even with their mutated and repulsive look, the Fleshes are still biologically pigs and therefore are safe for consumption (radiation poisoning notwithstanding). Some Stalkers take advantage of this fact by chopping their limbs and head off, skewering them onto a makeshift spit, and roasting the beast over a fire for food, similar to how roast pig is prepared.

Gameplay
Fleshes are the easiest mutant to face in the entire series. Their attack does little damage and though they travel and attack in groups, they're big and slow targets. Furthermore, when running towards the player they do so head first which makes headshots almost a given. In Clear Sky and Call of Pripyat they can be dispatched with nothing but a knife, saving ammunition. Just like Blind Dogs, Fleshes will panic and run away when some members of the pack die unless when led by a Boar or the "Alpha Pig".