Headcrabs vs Xenomorphs; Uncovering which is the Superior Parasite
In my quest to obtain forbidden knowledge I have discovered the secret to interdimensional travel. I only accidentally caused a single very minor potentially apocalyptic resonance cascade. But I recontained it so it’s fine! Actually, that was one of my arch nemeses who heroically sacrificed themselves by diving into the portal to defeat a pandimensional elder god that was holding open the tear in the fabric of reality with psychic might alone.
Long story short; I have discovered the multiverse. It’s the collection of every ‘pataphysical plane of existence. If you have a fictional setting, I can physically go there. I haven’t managed to travel vertically through ‘pataphysical layers so I can’t go to nonfictional planes of existence, yet. Though I have been able to put this blog on the 3rd dimension’s internet.
The best part is it’s very easy to use. You just type in the name of the fictional property and it opens a portal there. The safe kind. No risk of eldritch beings here.
The only issue is that I don’t know anything about fiction. Despite having several PhDs in literature, I don’t watch a lot of movies, or play games, or go to parties. I kinda just do science all the time. Very unhealthy, I know.
Anyways, during my expeditions, I’ve found two species which are surprisingly similar. Like, whatever deities or fifth dimensional entities running the simulations must have copied off each other. Both are great candidates for biological weapon research. But building that transdimensional travel device was pretty expensive and we had a lot of not entirely unrelated incidental costs this year. We’re several billion dollars in the red so I have to ax one of the two programs.
Obviously, the best way to decide which is better is with a massive death battle. Though, that would also be pretty expensive now that I’m thinking about it. I’d probably need another nuke to recontain that.
How about I just keep it to a thought experiment? And by “I” I mean “you”. Most of my research staff died in a recent containment breach so I’m outsourcing this mental labor to unpaid complete strangers on the internet. Let’s get a discussion going in the comments!
Headcrabs vs xenomorphs, who would win? Since both need humans to propagate, the hypothetical battleground would be the entire planet. Historically, the only thing that can stop either’s growth is some pesky protagonist. So we’ll assume there are no main characters to get in the way. Humans will certainly resist, but ultimately they’re just a resource for the two parasites to fight over.
By the way, we aren’t considering any “expanded universe lore” or “headcrab varieties”. If we did we’d be here all day. Also, I don’t have any of those. Just the normal run of the mill bugs. Assume both factions are starting from just one queen and one gonarch. It’s not just a question of which is better at fighting. Which is better and faster at spreading also matters.
I’ve attached the relevant data on the two in a format you’d be able to understand. Aka, casual and humorous.
Table of Contents:
Headcrabs
My Nemesister wants me to play this video game, Half-Life? Like radioactive decay. Apparently, the main protagonist is a scientist, which is cool. I’m sure it’s safe to go there. Surely there isn’t anything in that fictional universe that could massively backfire just from going there. Like some sort of extremely powerful interdimensional empire, for instance. It’s fine.
I discovered what she calls “headcrabs” in a weird space dimension with lots of floating islands and that has constant directional gravity and breathable air somehow. At first the headcrabs just seemed like some unassuming scavenger at the bottom of the food chain. They like to burrow and hunt things smaller than them, which considering they’re the size of a turkey, isn’t much.
That was until one of my henchmen (Jimothy, rest in peace) got too close. It jumped onto and engulfed his head inside its mouth. A beak quickly punctured his skull, paralyzing him. At first I just thought it was just trying to bite his head off. But in a matter of minutes it had interfaced with his nervous system and began piloting his body like a meat puppet. It also rapidly and radically altered his body’s physiology, turning his fingers into claws and creating a faux maw in his chest cavity. Yeah, an extradimensional turkey crab can latch onto your head and turn you into a zombie. I wouldn’t believe it either unless I wasn’t still getting nightmares after seeing it.
The worst part is that this doesn’t actually kill the host. The initial bite targets the brain stem paralyzing the victim from the neck down but not killing them. But the victim still tends to still have control of their own mouth and can speak even after the crab starts piloting their body. A lot of what they say is pretty muffled by the crab on their face and also garbled from all the brain damage. But yeah, if you set a zombie on fire in self defense they’ll scream in pain and beg for mercy from God. Since they’re probably also your comrade or friend these aren’t fun to fight in real life, no.
I’m a comically evil stereotypical mad scientist super villain. But even I don’t like seeing my henchmen subjected to a fate like that. The Henching Union would sue the crap out of me if I didn’t do anything about it. But I’ve never found any way to reverse this zombification or even to remove the headcrab without immediately killing what remains of the host’s brain.
Now, I know that I just said all the horrific things headcrabs want to do to you. But here me out. They make great pets (as long as you debeak and spay/neuter them). Headcrabs can be pretty cute even when they’re trying to kill you. They make these little chirping noises and if they jump at you and miss they might land upside down and need to flop around trying to right themselves.
Headcrab Zombie
The zombie transformation happening within minutes is consistent with the Half-Life games. My Nemesister says that during the canal level of Half-Life 2 a rebel outpost is completely turned into zombies within minutes of getting shelled. Apparently the bad guys in that game use headcrabs as a bioweapon in the form of giant crab filled artillery shells. Not a bad idea.
After the host grows claws, the headcrab’s influence forces them to tear open their own chest cavity. Despite bleeding about as much as you would expect from this they never bleed out. They can get cut in half and still crawl and fight for extended periods. Zombie blood can be seen with weird yellow globules in it. So I’m guessing that the headcrab injects some sort of highly efficient coagulant into the host’s blood that can prevent torrential bleeding and fight infection.
The leading hypothesis on why they tear open their chest is to access the stomach. See, the headcrab covers the head so the zombie can’t use their mouth to eat. So the headcrab just creates a new opening to their stomach and places food directly into it. They have been seen feeding like this in the original Half-Life game. This is the kind of out of the box straight to the point problem solving I want to see more of in my evil science organization. Can’t access the mouth? Just make a new one. Genius.
Both headcrabs and zombies are ambush predators. Crabs will occasionally jump down onto victims from high places, especially over doorways. They bury themselves in sand and pop out when someone walks near them. Zombies will play dead, which is convincing as they’re generally surrounded by corpses in as bad a state as they, only to get up when someone walks near them. I’m unsure if this hiding and ambush behavior is purely instinctual or indicative of higher intelligence. The headcrabs must have more brain power than you would expect of something their size to be able to control a human body. They are smart enough to throw things at their prey. So they’re at least as smart as a monkey.
The zombies display superhuman strength, able to slap steel oil drums hard enough to send them flying 20 feet. This is easy to explain as the crab cranking up adrenalin production.
Unlike most animals, humans don’t actually use all the muscle fibers in a muscle at once. Instead, we just have some muscle fibers firing while the others rest. This massively improves our physical endurance, combined with how efficient sweating is when you have no fur, gives us the longest running endurance of any land animal. That is not an exaggeration, no other naturally occurring species can run a marathon. As if humans weren’t already overpowered enough.
But the drawback is that, since we don’t use our full potential strength, our tendons and ligaments aren’t generally strong enough to withstand that much force. So when you get really hoped up on adrenalin, which unlocks your full strength allowing you to do things like lift a car off your baby, you’ll probably injure yourself in the process. But the headcrab doesn’t care about that since the host body is disposable to them.
Headcrab Paradox
Headcrabs seem to be better adapted to human biology than most of our actual parasites. Which is strange, right? Presumably, headcrabs should never have encountered a human before now? I mean, they’re from another dimension. One where evolution clearly took a very different course to ours. There aren’t any humans there. And it’s not like they have this behavior with any other species from their dimension. I’ve never seen any vortigaunt zombies or anything. They only do this with humans. How did they evolve this?
I know I said we wouldn’t be talking about other types of crab, but bear with me. In Half-Life: Alyx you encounter a new species of alien which is somewhat distantly related to more familiar headcrabs but is still part of that family. It has a bioelectric organ (like what electric eels have) capable of producing such massive amounts of power that it can create electrical arcs as its most basic line of defense against predators. The organ is capable of powering advanced technology even when removed from the dog’s body.
Notably, lightning dogs like to climb into the chest cavity of abandoned headcrab zombie corpses and pilot them like a meat puppet using galvanism. Galvanism is the act of forcing a muscle to contract with electricity. Disregarding how many laws of thermodynamics are being broken here, this does make some evolutionary sense. Carnivores in the wild often have to fight over carcasses. A smaller scavenger could benefit from the ability to crawl inside one and use it to fight off competitors, especially if the meat gets cooked in the process.
I hypothesize that the lightning dog resembles the ancestor of all headcrabs. Perhaps headcrabs then evolved to specialize in controlling still living hosts through controlled electric stimulation onto regions of the brain or major nerves. The benefit being that living hosts last longer and can heal and grow. Though this would require them to massively reduce their electrical output to not cause undo damage to the host nervous system, which is why crabs don’t have any sort of electrical attack. If this were true, it might help explain how headcrabs are able to so easily control a body that should be entirely alien to them. If you poke something with an electric stick enough it’s bound to do something. That still doesn’t explain why they only do this with humans or how they cause the host to grow claws. But it’s something.
Zombine
You generally don’t want headcrabs latching onto soldiers. Especially not if they’re cybernetically augmented super soldiers like some of my henchmen are. Because then you’ll get soldier zombies. (or “Zombine” as Nemesister calls them for some reason. Silly name).
Not only do soldiers tend to be stronger and tougher than the average civilian, but they also are often wearing bullet resistant armor. So you would expect soldier zombies to generally be a bit tougher. Unfortunately helmets don’t seem to do anything to stop them. Headcrabs have a very strong bite.
If their radio gets stuck on the poor soldier will probably occupy their time being a prisoner in their own body by mumbling to dispatch. While this often gives tactically useful information, it’s not great for the morale of everyone else on the radio.
Remember how I said that headcrab zombies are smart enough to throw things? They can also sometimes pull the pin on grenades. But they can’t do those things simultaneously for some reason, so they just try to suicide bomb the player. I’m not sure if this is because the headcrab is smart enough to operate grenades or if the canonical cybernetically augmented and indoctrinated supersoldier wrestles back control for a second to kill both themself and the player. None of my henchmen-turned-zombies did this, but of course they wouldn’t. We can’t afford grenades.
Gonarch
The wild headcrabs have a life cycle involving a much larger sexually mature form called a gonarch (a portmanteau of monarch and gonad. If you really want to know, look up a picture of it.) It’s about the size of a small house. Honestly, I have no idea how you get from a chicken sized headcrab to that. I’ve never found any transitionary form or chrysalis or anything.
They are capable of giving birth to an alarming number of baby headcrabs frighteningly quickly. So fast that their combat strategy revolves around giving birth during combat so the newborns can kamikaze run into the nearest threat. Despite this, they loudly scream in mourning whenever their babies are killed in front of them. So I’d imagine that giving birth is just an involuntary reflex to stress or fear, and they don’t actually want to risk their young.
This may be similar to quokkas throwing their babies at predators to escape. In real life, quokkas are an adorable marsupial species. Like most marsupials, they carry their babies in a pouch on their belly. But when a quokka is surprised, the muscles in her pouch involuntarily relax causing the baby to fall out. If they were surprised by a predator the quokka mother will be too busy running away to pick them back up, leaving the helpless baby to distract the predator by being an easy meal. While sad, evolutionarily speaking it’s better to lose the baby than the baby maker.
Since we never see baby headcrabs outside of fights with gonarchs, it can be assumed that the babies mature fairly quickly.
The gonarch can also run pretty quickly and their thick exoskeletons make them pretty tough. The only way I (my legions of expendable Henchmen) have managed to kill one was with copious amounts of high explosive ordinance. Serendipitously, there was already plenty of military grade munitions and medical supplies just lying on the ground nearby.
Gonarchs also projectile vomit from an orifice on the top of her cephalothorax in self defense. This acidic bile is devastating against other species from its dimension and humans not wearing proper protective equipment. It’s still pretty damaging even if you are. However, both baby headcrabs and normal headcrabs seem to be immune to it. Headcrabs getting caught in the vomit splash but remaining unaffected is something we also see happen in the original Half-Life game.
We also see headcrabs hiding while submerged in toxic sludge in HL2. While this sludge is radioactive as evidenced by the protagonist’s geiger counter, the fact that it only damages him on contact and that it fumes suggests it’s also highly caustic. While I would imagine they evolved such strong acid resistance to survive their own mother’s friendly fire, it remains of great use to them even in new environments. They also confer this resistance to the zombie host as we see them also sleeping underneath toxic sludge. Despite being able to survive submerged in strong acid for extended periods of time, headcrabs cannot swim and immediately drown when dropped in deep pools of water. Good luck explaining that.
Xenomorphs
Xenomorphs are the aliens seen in the creatively named Alien movies. They are the perfect predator, seemingly too perfect. Heads up, I haven’t watched the Alien movies either. They’re on my watch list, right after Cloudy with a Chance of Meatballs, okay? I’ll get to it.
Xenomorphs were actually pretty hard to find. They’re not that common in their home universe since protagonists there have been pretty good at stopping them so far. We actually had to buy some off another evil science organization called the Weyland-Yutani Corporation. #notsponsored, but it was genuinely a pleasure doing business with them. I would recommend their services if any of you find yourselves in that part of the multiverse.
Of course with my luck it couldn’t have gone that easy. Once we got back to earth we might have had a small, very minor, some may say insignificant, massive containment breach. And the xenomorphs might have slaughtered everyone inside the facility. And then I might have stalled recontainment efforts until after I could recover a sample. And because of that they might have had time to also kill everyone in a nearby town. And I might have had to use several nukes to stop them from ending all life on earth as we know it. That wasn’t easy to cover up. But you know what? I was the one who saved the world this time. Me. I did that. You’re welcome.
Anyways, that little incident gave me the perfect opportunity to observe the xenomorph life cycle and assess their potential as a biological weapon.
Life Cycle
The xenomorphs have an incredibly interesting life cycle. They start as a weird fleshy egg. If someone gets too close to an egg it opens like a flower revealing a facehugger. Can you guess what the facehugger does? That’s right, it hugs your face. This is far worse than it sounds.
I swear, those weird bald aliens that created the xenomorphs must have been trying to invoke rape imagery or something. The facehugger’s legs look like fingers, its weird sack things look like balls, it shoves an ovipositor down your throat and impregnates you with another egg. Now that I think of it, the headcrabs are oddly sexual as well.
Anyways, after about a day the facehugger finally lets go of your face. It’s been the one thing keeping you alive all that time since you were unconscious and couldn’t breathe. You might feel okay at this point, but you’re really not. Because some indeterminate amount of time from now a chestburster is going to do its thing. Can you guess what that is? Burst through your chest? That’s right! These goddamn names are great. Could you imagine if we named earth animals like that? So after the chestburster does that, you will almost certainly die from the trauma. Then the chestburster worm thing fucks off inside the walls and slowly grows into an adult.
It will take a longer indeterminate amount of time for it to grow, but still pretty unbelievably quickly. It’s going from a six inch long worm to a seven foot (upwards of 2 meters) tall monster in, like, a few days? I don’t know if it even eats anything during that time. In the first movie they never showed any signs of it stealing food or anything. It didn’t even eat the cat. Where’s all the mass coming from?
So you’re already dead. But now your friends are fucked. The xenomorph drones are really scary. After the drone comes the queen, which is like a queen bee. They are absolutely huge and pump out eggs in large numbers.
So why do they do all that? Seems like an awfully convoluted life cycle. What’s with the facehugger thing in the middle? I believe that is actually the secret to their success and makes them the perfect invasive species.
The facehugger isn’t just laying an egg in you for the normal reasons why things like parasitic wasps lay eggs in living victims (incubation, giving young a meal as soon as they’re born). It’s also stealing your genes.
The adult xenomorph drone that the chestburster grows into will share certain traits with the host. For instance, if it came from a dog it will walk around on all fours. But it’s also getting the ability to breathe your planet’s air. Properly digest your food. Etc. No one species could survive on multiple alien worlds unless they could adapt as quickly as this.
Bugs
The folks at Weyland-Yutani warned us they have acid for blood. And they weren’t kidding. Xenomorphs bleed one of the strongest acids in existence. Pretty good defense mechanism. Though I doubt its blood. If you’ve been to med school or are a bio major, you might know how important balancing acid/base chemistry is in the blood. You might know it so well that you’re getting ‘nam flashbacks right now.
So how exactly would their equivalent of kidneys, or liver, or anything really work having the strongest acid in existence as blood? Maybe it’s actually something like lymph or some other fluid which exists purely for this defense mechanism that’s separate from their vascular system. Maybe it’s stomach acid and their stomach is sandwiched between their skin and internal organs. I don’t know for sure. I can’t dissect them. Y’know, acid.
The xenomorphs are surprisingly smart. Not enough to use tools, but they’ll do everything short of that. They never seem to fight unless they have the advantage. They are very sneaky alone, but in large numbers, they attack en masse. But honestly, unless your friends have guns, they wouldn’t even need to do those things. The xenomorph drone is physically superior to a human in every way. But yeah, they die pretty quickly from bullets.
Their teeth and claws are made of metal, which is impressive. On earth, there aren’t any known species which can produce metallic metal besides humans, but we cheat. Most species use metals in some chemical form, but not as an elemental solid.
Xenomorphs are eusocial, which means they have a hivemind like ants or bees. They will cooperate and sacrifice themselves for the needs of the group, if need be.
Meanwhile, headcrabs are semisocial at best. They are good at tolerating each other’s presence and like to congregate in groups. But ultimately they lack any ability to cooperate and will act selfishly if push comes to shove. Except when they’re babies. Then they seem to prioritize their mother’s survival over their own. But they seem to lose that mentality upon adulthood.
Humans are far worse, are you kidding? Not only are we bad at cooperating, but we actively screw each other over. Even the headcrabs are better than that.
I would love to believe that xenomorphs are the product of evolution. That the dark universe is a place so uncaring that such horrors can come into existence without meaning. That millions or even billions of years of natural selection will produce the perfect predator. A predator whose ecological niche is spreading through the galaxy on the ships of intelligent species and devouring entire planetary ecosystems. The implication that this is the great filter; the reason why humanity has yet to make contact with aliens like us is because aliens like the xenomorph also exist. But Nemesister tells me that in the recent movies it’s revealed they’re actually a bioweapon that comes from goo made by bald aliens who seeded humanity, which is incredibly disappointing.
Discussion
Sorry if you clicked on this article wanting a concrete answer on which is better, but as I said, I don’t know. Ultimately, the question of headcrabs vs xenomorphs comes down to a contest between quantity and quality.
Obviously, a single xenomorph is much more likely to kill a single zombie than the vice versa (unless that zombie has a grenade or gets in a lucky claw swipe). But Headcrabs spread far faster than xenomorphs. Headcrab zombification takes only minutes. Whereas with xenomorphs we’ve seen that the facehugger needs to stay on a victim for like, a day. The chest-burster doesn’t come out for a while after that. And it’s another long while for the chestburster to grow into an adult.
By the time there is a single fully grown xenomorph drone there will already be a huge horde of headcrab zombies. The remaining humans will already be in the process of arming themselves, fortifying, and on the lookout for all sneaky diminutive beige-colored head humpers. That first generation of xenomorphs will have a harder time building the nest and kidnapping enough hosts to make the second generation. They will always be significantly outnumbered by zombies, which they likely can’t impregnate with facehuggers thanks to the whole mouth complication.
Zombies also shouldn’t be underestimated. They can keep fighting even with much more grievous wounds than xenomorphs can tolerate. They can also throw things giving them marginally superior ranged capability. Headcrabs are also resistant to acid, countering the xenomorphs’ ultimate defense.
So which is more important? Quality vs quantity? Headcrabs vs xenomorphs? Answer in the comments below.
