Let's get this question right out in the open: Why don't they just shoot the alien? We assume that it follows the rules of most creatures, live or undead—shoot it in the head and it's toast.
Only problem is, the creature's blood is so acidic that a drop of the stuff almost ate through the ship's hull. An exit wound's worth would no doubt inhibit the Nostromo's space-faring abilities.
That means it's time to get creative.
Fire to Destroy All You've Done
The crew collects a number of tools to confront the alien, and funny thing is that, although this is a futuristic spaceship, the tools all harken back to humanity's hunter and gatherer days.
Let's run down the tools of their trade:
- The cattle prod has a distinct spear-like look to it. It operates much like a spear—very jabby—but with a bit more of a jolting presence.
- During the first hunt, we see Parker with a net, a total throwback to the tools of our ancestors. It doesn't have any high-tech upgrades; you don't mess with the classics.
- The motion tracker allows the crew to track down the alien. The device picks up "micro changes in air density," means that the crew doesn't have to look for tracks or scat. But the idea is essentially the same.
- Finally, the flamethrower provides fire. Fire has long since been regarded as a symbol of man's ability to control nature and terrify the animals we share earth with. In Greek mythology, Prometheus was considered the champion of mankind for giving us the stuff. In The Jungle Book, Mowgli's Brothers teach that every beast lives in deadly fear of fire. Ash even says, "Most animals retreat from fire, yes?" (Alien).
These tools might be higher tech than what was available to our ancestors, but the imagery reminds us of an age when mankind hadn't completely dominated nature. If you wanted to kill a lion back then, you had to get within spearing distance of the creature—no guided big-game tours available.
This imagery helps us understand the predicament of the Nostromo crew. Their technology gives them a fighting chance against the alien, but like our hunter-gatherer ancestors, they aren't exactly at the top of the food chain any longer.