Editing Xenomorph (section)

===Physiology===
Alien blood contains concentrated [[hydrofluoric acid]] and [[sulfuric acid]] and is capable of corroding almost any substance on contact with alarming speed. It is dull yellow in color and appears to be pressurized inside the body so that it spurts out with great force when the creature is wounded. [[Ron Cobb]] suggested the idea of the Alien having acidic blood as a plausible means to make the creature "unkillable"; if one were to use traditional firearms or explosives to attack it, its blood would eat through the hull of the ship.<ref>''Alien'' commentary, Alien Quadrilogy boxset</ref> The ''Alien'' novelization suggests that, at least at the "facehugger" stage, the acid is not blood but a fluid maintained under pressure between a double layer of skin.<ref name="fluidnotblood">{{Cite book | last1 =Foster | first1 =Alan Dean | author-link =Alan Dean Foster | last2 =O'Bannon | first2 =Dan | author2-link =Dan O'Bannon | date = 1979 | title =Alien | publisher=Macdonald and Jane's | isbn =0-354-04436-2 | location =London }}</ref> In the ''Aliens vs. Predator: Requiem'' documentary "Science of the Alien", it is hypothesized that the Aliens' acid blood could contain [[sulfuric acid]] due to its corrosiveness and the conspicuously toxic effects on living human tissue. The documentary also speculates that Aliens are immune to their own acidic and toxic liquids due to an endobiological build-up, similar to the human stomach's ability to protect itself from its own digestive fluids. The documentary takes this hypothesis one step further and speculates that the Alien organism's protection system against its own acidic blood is a bio-organically produced [[Teflon]]-like insulation.<ref>[Shane Salerno (writer) Colin and Greg Strause (directors). (2008). ''Aliens vs. Predator: Requiem'' [DVD]. 20th Century Fox.]</ref> In the original ''Alien'', the facehugger is shown to be able to "spit" acid, dissolving the faceplate of Kane's helmet and allowing the creature immediate access inside. This ability is also exhibited by adult Aliens in ''Alien 3'' and ''Alien Resurrection''; much like a [[spitting cobra]], they use it to blind their victims.<ref name="A3"/><ref name="A4">{{Cite AV media|people=[[Joss Whedon]] (writer) and [[Jean-Pierre Jeunet]]|title=''[[Alien Resurrection]]''|medium=DVD|publisher=[[20th Century Fox]]|date=1997}}</ref>

Aliens can produce a thick, strong [[resin]] that they use to build their hives and to [[Cocoon (silk)|cocoon]] their victims, and they can use the walls of their hives as [[camouflage]].<ref name="MacFarland">{{cite book|last1=Sipos|first1=Thomas|title=Horror Film Aesthetics: Creating the Visual Language of Fear|date=2010|publisher=MacFarland|isbn=978-0786458349|page=80|ref=SiposBook}}</ref> Aliens also salivate heavily in the form of a sticky, clear slime; while not a toxic substance in and of itself, it is common for the ''Alien'' films to use it as a suspense-building device, wherein a character will notice the falling saliva before noticing its source lying in wait above them.<ref name="MacFarland"/>