Why do the Aliens constantly seep slime out of all their body parts all the time? How could they drink enough liquids on a barren planet to have enough moisture in their bodies to leak all over all the time, and what purpose does it serve?

  • 5
    Although I am sure in-universe explanations can be found, and the end of the day it's probably all down to most of the consumers of the movie being appalled by the slime. :)
    – sbi
    Mar 27, 2012 at 8:56
  • 2
    I remember watching a documentary on how "The Thing" was made they found the models just didn't look convincing unless they had moisture on them hence covering them in ky jelly. I am sure when they were making alien they found the same thing. May 30, 2014 at 12:33
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    In the first film there is some slime around around the alien's mouth; however, in that weird space in the Nostromo with the hanging chains and dripping water where Harry Dean Stanton's character is killed, we see the water running over the alien's head and dripping from the mouth like drool. I believe the makers of subsequent films thought this looked cool and incorporated it as part of the alien's behaviour.
    – Mr_Thyroid
    May 26, 2017 at 15:50
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    Wait, you're wondering how a monster that grows from the size of a ferret to about three meters tall in under 12 hours, without eating, can produce slime?
    – Damon
    Nov 11, 2017 at 20:01

4 Answers 4


The resinous slime is used to cocoon hosts, holding them immobile so facehuggers can easily impregnate them. We saw Ripley pulling this goop off Newt in Aliens shortly after dispatching an emerging facehugger.

The Alien's highly acidic body chemistry might explain the excessive resin secretions, as some synthetic resins are produced by chemical processes involving strong acids and organic compounds. A typical byproduct of the neutralization of acid in such reactions is water.

  • The second answer sounds more likely to me, because why not excrete large amounts of it when it's time to cocoon up a host, rather than just leeching it onto the floor all day. But I really like your second answer. Thanks for answering!
    – SpaceNinja
    Mar 26, 2012 at 22:57
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    Another possibility is that it's building material for the caverns they build in old spaceships. Remember how the walls become more and more like an H.R.Giger painting, with an organic ribcage motif? They might constantly add to it as they slime by, and in their free time, mold it into those shapes.
    – SpaceNinja
    Mar 26, 2012 at 22:59

If I had to guess (and it's just a guess) I'd say the slime they secrete serves to negate the acid in their blood. You don't want a whole hive melting because one worker got a papercut.


We don't know that the slime is a water-based liquid that would require moisture. It could be something like glycerin, which is slimy, oozy, thick, and slippery and perfect for general yuckiness. There's no water in glycerin.

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It probably also serves as some sort of "marking" abilities as well. A dog doesn't necessarily need to pee over everything, and a cat need not leave their hair everywhere, but doing so marks their territory and sends messages to others of their species. Given the xenomorph predatory behavior, it wouldn't surprise me if the slime also works to help them track victims. If you start smelling your type of slime in an area you haven't bedaubed, odds are that potential prey is tracking it around.

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