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Whither aliens without food?
February 12, 2013 1:14 AM   Subscribe

Just finished watching the Alien series (again). I've always been curious, what did they live on for sustenance? Their awesome power and quickness suggests a significant need of caloric intake, but how this was handled was never clear.

Humans were either dismembered (but not devoured) or cocooned for the purposes of becoming gestative hosts. Also, the Aliens seemed to secrete substances that enabled them to build vast nests. But still no clue as to the energy source of this. Any clues?
posted by psmealey to Media & Arts (15 answers total) 9 users marked this as a favorite
The novelisations are pretty clear that the crew and colonists are eaten as well as used as hosts.

When the drones bash a human's head in with the mouthparts (ewwwww!) that would presumably make them useless as a host for a facehugger.

So assume at least some of these get eaten.
posted by tonylord at 1:23 AM on February 12, 2013 [1 favorite]

They are weaponized batteries.
posted by fleacircus at 1:28 AM on February 12, 2013 [3 favorites]

I bet those fuckers ate metal.
posted by Specklet at 1:32 AM on February 12, 2013 [2 favorites]

Well - they bled ludicrously strong "molecular acid" - so there is a question about what they were made of which would allow them to have that as blood without being destroyed. If you have a really strong acid then the best sort of material to hold it is glass. So I am going to say that they were made of Pyrex and fed exclusively on oven ready meals. The whole hunting slaying and maiming thing was just what they did to stay in shape.
posted by rongorongo at 1:57 AM on February 12, 2013 [27 favorites]

I hate to break it to you, but the Xenomorphs are real.

Well, at least they are based on real parasitoid creatures and so to get a good answer to this kind of question you can just look at those parasitoid life cycles - I made a huge post about one of them a little while ago that you might be interested in. Hymenopteran parasitoids, and indeed most parasitoids with similar life cycles, for the most part have pretty unremarkable diets during their adult sexual stages. The adult xenomorph-like Hymenoptera largely get their calories from nectar and honeydew secretions1. Watching the original movie as a grad student I just assumed the maturing adult critter was raiding a emergency food store on the ship or chowing down on something else that is calorie dense.
1Wäckers FL (2005) Suitability of (extra-)floral nectar, pollen, and honeydew as insect food sources. Plant-provided Food for Carnivorous Insects (ed. by FLWäckers, PCJVan Rijn & JBruin), pp. 17–74. Cambridge University Press, Cambridge, UK.
posted by Blasdelb at 3:49 AM on February 12, 2013 [31 favorites]

Thank you Blasdelb. Your answer is exactly why I posed this crucial and important question on AskMeFi. Absolutely perfect.
posted by psmealey at 3:53 AM on February 12, 2013 [4 favorites]

Farmers use parasitoid wasps as weapons, just like the fictional Weyland corperation intended to, in order to turn their pests into face hugged incubators of more wasps; they can even order these things online nowadays.
posted by Blasdelb at 4:33 AM on February 12, 2013 [1 favorite]

In the original novelizations, by Alan Dean Foster, I recall that it was consuming humans.
posted by jadepearl at 5:02 AM on February 12, 2013

"Well - they bled ludicrously strong "molecular acid" - so there is a question about what they were made of which would allow them to have that as blood without being destroyed. If you have a really strong acid then the best sort of material to hold it is glass. So I am going to say that they were made of Pyrex and fed exclusively on oven ready meals."

Their life cycle as obligate parasitoids really is essential to the nature of the character though,

When I was a wee little undergrad once, long ago, I made my Gen Chem professor ludicrously happy by asking in class what a 'molecular acid' was and how acidic xenomorph blood would need to be to have such a corrosive effect while I was learning about how pH works for the first time. It turns out that ‘molecular acid’ means precisely nothing, as all acids are indeed molecules, and while many corrosive things have the acidic properties that is generally not what makes them corrosive – at least to metals. Ridley Scott was indeed just talking out of his ass in the same way that was more readily apparent to laymen in his more recent film.
Dallas: [looks at a pen being dissolved by alien's body fluid] I haven't seen anything like that except, uh, molecular acid.
Brett: It must be using it for blood.
Parker: It's got a wonderful defense mechanism. You don't dare kill it.

Bishop: The molecular acid oxidizes after the creature death, completely neutralizing it.
Even if we go with Both Dallas and Bishop are idiots instead of the obvious Ridley Scott is an idiot though, the kinds of chemistry necessary to corrode aluminum or steel alloys at standard temperature and pressure in seconds are pretty fundamentally incompatible with biological systems as we know them; or could conceivably interface with ours like theirs are shown doing. If they had terrifying shit like Uranium hexafluoride or God forbid FOOF running through their veins there would be no way for them to do anything other than start exploding on fluid contact with us, much less replicate in us. Indeed even the face-hugger stage critters had this 'molecular acid' blood.

Perhaps there is some kind of fucked up oxidative chemistry going on that is somehow segregated from their living systems? Or maybe their living chemistry is just fundamentally alien and they generate energy somehow from the violent reactions we see with biological molecules we are familiar with (ie: the crew)? While the second hypothesis would explain more, Bishop's observation would seem to make the first more plausible.

I have given way too much thought to this over the years.
posted by Blasdelb at 8:43 AM on February 12, 2013 [7 favorites]

From the "Alien" novelization:

They had to follow the shifting needles only a dozen metres before a louder, different sound became audible: metal tearing. Dallas cradled his flamethrower, turned the corner in the corridor. Loud rending noises continued, more clearly now. He knew where they were originating. 'The food locker,' he whispered back to them. 'It's inside.'
Packages of every size were strewn about the floor, opened in ways and by means their manufacturers had never envisioned. Solid-metal storage 'tins' had been peeled apart like fruit.

posted by martinrebas at 8:49 AM on February 12, 2013 [3 favorites]

I missed this originally. This wiki on Aliens was included in Blasdeb's fantastic Mefi post, mentioned above.
posted by psmealey at 1:02 PM on February 12, 2013

I think I remember that in the original Dark Horse comic book series it was mentioned somewhere that the used the bodies of their victims as either hosts or to construct their hives. They also ingested silicon to sustain their exoskeleton and maybe for producing their resin secretions. This also could have been from an Aliens role-playing game I had. I also might be making this all up.

What I think is curious is how do they grow so large so fast? Especially in the AvP series. In alien it went from chestburster to drone in a matter of a few hours or maybe a day and no crew members went missing until it was grown so it didn't eat any crew between birth and maturity.
posted by Che boludo! at 3:02 PM on February 12, 2013 [1 favorite]

The fast, and even larger growth was also evident in Prometheus when the Noomi Rapaces squid baby grew to a very large size locked in the medical bay with no access to food either. The food source they is most likely suspension of disbelief.
posted by Che boludo! at 3:05 PM on February 12, 2013 [1 favorite]

How could the aliens be so large and yet need so few calories? Well, cold-blooded/ectothermic animals use far less energy at rest. A crocodile may be the exact same weight as a cougar, yet has a much slower resting metabolism, and thus may only need one-tenth as much food to stay alive. The effect of this allows ectotherms to maintain stable breeding populations in desert habitats that don't have enough energy to support mammalian populations. Ectothermic aliens are more likely to be able to maintain stable populations in areas with little consistent food.

The downside of ectothermy is that cold-blooded animals can't keep up high-intensity activities, such as running or flying, up for very long. Ectotherms, however, can move very quickly for short bursts. Because of this, ectothermic predators tend to act as ambush predators. This strategy also has the benefit of using less energy than a more active hunting strategy. So the aliens could get by without food while still being strong and fast... at least in short bursts.

As for how a creature could grow from juvenile to adult without any food... I agree with Che, but it could be that the baby aliens still have some kind of extremely calorie-dense yolk sac that gives them enough energy to grow to juveniles, if not adults. Young fish of most species will carry around a yolk sac for some time after they hatch and are able to move freely. It seems unlikely that this yolk sac could be so small that it's not externally visible, and yet so calorie rich that an alien can use it to grow to maturity... but hey, it's Aliens, so lets roll with it.
posted by Green Winnebago at 8:27 PM on February 12, 2013 [1 favorite]

One of the source/spinoff/(roleplaying?) books I flicked through in a bookshop one time said they were indeed essentially big batteries.

I seem to remember the Alan Deam Foster novelisation of the first film (and/or maybe the original script - though it's years since I read it) had a scene where the crew discover that the alien has raided the ship's food store - with 'tin cans pealed open like bananas'
posted by fearfulsymmetry at 1:50 AM on February 13, 2013

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