With the Alien running loose on their ship, the crew of the Nostromo convene to talk tactics. “Most animals retreat from fire,” muses Ash. Later, in Alien 3, Ripley sighs that the creature is afraid of “fire, not much else.” Arguably, there is no indication within the films that this is true.
James Cameron noted in Starlog magazine that “we never see [flamethrowers] actually used against the creature” in the original film. Ash, always keen to throw off his crewmates and preserve the creature, may have simply been throwing them a red herring. When Dallas is in the vents, the Alien is not shy about snatching him, even though he is armed with fire.
At the end of Aliens, Ripley turns her flamethrower on the Alien Queen’s nest, who in return shows no fear, but only concern for her brood and contempt for Ripley’s daring. The burning hive does not deter any lingering Aliens from attacking Ripley, who cuts them down with her pulse rifle. When the Queen lunges for Ripley and Newt within the elevator, Ripley lets loose with a spray from her flamethrower. The Queen (again, arguably) does not recoil in fear, but screeches in anger. When the prisoners attempt to trap the Alien in the third movie, they set fire to the underground network of corridors. Their plan is to use the flames to beat the Alien into a vault. When the creature emerges it leers at Ripley and the prisoners, and is only locked away when prisoner Junior uses himself as living bait. Again, no real indication that the fire fazes the Alien.
The Alien drops Lambert.
Parker lands a blow with the flamethrower.
The Alien strikes him once.
Killing him instantly.
~ Alien script, final/revised, June 1978.
A point of contention may be one scene Alien 3, where Ripley, having trapped the Alien in a nook, waves a flare at the creature and attempts to grab its tail. The Alien, not willing to outright harm her (she is carrying its Queen, after all), screeches and claws at the flame. But is the Alien afraid of the fire, or angry at being closed in upon? Ripley’s aim is to bait the creature into the open, so why force it further away with fire? The Alien only moves out of its corner when Dillon takes hold of Ripley and drags her away.
Could fire even harm the Alien? Here is how Ash describes the physical make-up of the facehugger to Ripley: “He has an outer layer of protein polysaccharides. He has a funny habit of shedding his cells and replacing them with polarised silicon, which gives him a prolonged resistance to adverse environmental conditions. It’s an interesting combination of elements, making him a … tough little son of a bitch.”
The polysaccharide comment may be a nod to bacteria, which secretes protective layers of slime, usually composed of polysaccharides and protein, to help the bacteria protect itself from antibiotics and even chemical sterilisation. Such layers also serve as an aid in attaching bacteria to other cells, and also as food, or rather, energy stores. The facehugger could well be using such a protective coating, which not only serves to protect the organism, but to keep it energised (they do face a potentially long hibernation) and to help any regenerative healing properties … Either that, or the scriptwriters thought it sounded like an intelligent thing for Ash to say.
Either way, the facehugger is set up to be, as Ash says, a tough little son of a bitch. The adult Alien, by no stretch of the imagination, is even more resilient. The facehugger’s cells are also said to be made up of silicon. HG Wells, in an article written for the Saturday Review in 1894, turned his imagination to silicon-based lifeforms, and he gives a clear idea of how resistant such a being would be: “visions of silicon-aluminium organisms … wandering through an atmosphere of gaseous sulphur … by the shores of a sea of liquid iron, some thousand degrees or so above the temperature of a blast furnace.” As we seen at the climax of Alien 3, the Alien leaps from the molten steel – intact and furious. But afraid?
Pain and Fear: In Alien Resurrection, the Aliens are imprisoned and subjected to barrages of pressurised liquid nitrogen(?) by Dr. Gediman. They feign obedience and later escape, and though the punishment inflicted on them is clearly physically distressing (they shriek in pain and display anger) they seem to fake fear and obedience to trick Gediman into thinking they can be domesticated.
Of course, there are or seem to be inconsistencies in the Alien’s resilience. The original Alien is harmed by a speartip, and the monster in the third film bounces back after being crushed and submerged under molten lead. A jarring inconsistency? Harry Houdini was allegedly killed with a gut-punch, but Phineas Gage survived the trauma of an iron rod impaling his head. “The iron entered on the side of his face … passing back of the left eye, and out at the top of the head.” Almost immediately after his accident, “a teacupful of the brain” poured out when Gage vomited. He lived for another twelve years.
Of course, the point here is not that the Alien is invulnerable (it isn’t), but if it fears bodily harm. Looking at the first three movies, there seems to be no real (or at least, overpowering) evidence within the films that the Aliens are afraid of fire, other than from the characters’ unconvincing testimony.
The last word here goes to Ridley Scott, from an 1984 interview in Omni’s Screen Flights: “In relation to humans, the Alien does seem indestructible. It does not fear anything,” (emphasis in original.)