So I have this idea for this unique species of jumping spider.

Basically it is around a foot long/medium sized hat size and has pretty big fangs for its size. It jumps on to people's heads and uses these fangs to bite through the skull of humans(and maybe other similar creatures like gorillas) and injects a mind control venom into the head. Somehow, this allows for it to maneuver the host like the rat from Ratatouille.

Then it uses the host as a tool to gather and in some/many cases cultivate fruit for the spider and a home for its young(they are laid in fruits like pumpkins, also they reproduce asexually). They also use in to defend themselves from harm and from others things stealing its food.

Now at first, pretty much any fruit at least as big as an apple was game for it. But then I thought that it mainly going for avocados would be a better idea as it has both the fat and protein(I think they have a decent amount of it) that other fruits lack or are low in since an IRL mostly herbivorous jumping spider eats something similar.

My only real doubts about this is that avocados probably take a while to grow and that the host has its own needs.

These are not really a naturally occurring species, whether they are a GMO creature gone wrong or a freak sudden mutation brought on by some kind of bizarre incident, I have not decided.

How likely is this species method of survival going to work out given that they are somewhat similar to other jumping spiders barring their size, diet, and behavior?

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    $\begingroup$ this part is impossible. "this allows for it to maneuver the host like the rat from Ratatouille." $\endgroup$
    – John
    Mar 7, 2023 at 21:59
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    $\begingroup$ Unless there is [Magic] involved... Besides, a human skull is a pretty difficult thing for any critter to bite through. Basically, only a hyaena, lion or tiger might be able to manage it. A foot-long spider, no. $\endgroup$
    – Monty Wild
    Mar 7, 2023 at 22:03
  • $\begingroup$ I mean assuming it has proportional bite strength as normal sized jumping spider(plus more because of its strong fang muscles), is it more realistic? @MontyWild $\endgroup$ Mar 7, 2023 at 22:17
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    $\begingroup$ Have you thought about basing your monsters on wasps instead of spiders? Parasitic wasps do mind-control their hosts and fig wasps do have a mutualist relationship with a fruiting plant, so the creature would have more on real world similarities. Also, a giant wasp could also get a stinger into a human brain without needing to break though the skull. This change wouldn't solve all your problems, but it would fix some of them. $\endgroup$
    – E Tam
    Mar 8, 2023 at 3:10
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    $\begingroup$ It maybe could work as a symbiotic relationship, the humans have a spider on their heads as an extra set of spider eyes, useful in hunts and in fights. $\endgroup$
    – Ivana
    Mar 8, 2023 at 10:30

6 Answers 6


The spider wouldn't thrive

The spider has two weaknesses. First is the fruit. If the fruit supply is halted, the species is in grave danger. The second is angering humans. As so many species have learned, often enough by selective evolution, you do not f*ck with humans. It is thought that this is one (of several) reasons why many larger predators do not attack humans. Any that did engaged the wrath of humans. They were generally removed from the gene pool before they could reproduce. Animals of such species that did not attack humans thus had a larger chance to succeed.

If such a spider would attack humans it would be noticed very quickly. Humans are a social species that often check on each other and knows the specific behaviours. If someone was missing, turned up with a big spider on their head or did some weird stuff it would be noticed and acted upon mear instantly. The spiders are likely outnumbered and will be killed in short order.

The defence of the fruit is also a big indicator how they reproduce. It wouldn't be unthinkable that humans start burning any and all fruit related to the spider. If not destroy it, they will restrict access and control who can cultivate it. This will lead quickly to a no win scenario.

Finally the humans will also protect themselves. As FluidCode mentions in the comments, humans will find ways to protect themselves. A simple helmet might suffice.

In the end you have a relatively big spider, dependent on humans and a fruit, to keep humans in control for the time they try to reproduce on that fruit. Numbers will barely matter. Taking over a few secretly or trying a whole town at once is too fraught with danger. Other humans will find out. They will be horrified. They will go to arms. They will obliterate the spiders, the fruit and if needed the hosts swiftly and harshly. Sure it'll make for excellent drama, but the spider will barely manage a second generation.

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    $\begingroup$ Exactly my first thought: Humans gonna get their Extinction game on. $\endgroup$ Mar 8, 2023 at 6:08
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    $\begingroup$ Small detail to be added to @Trioxidane answer. Once humans see what happens to other humans they'll likely begin to wear helmets when they go in areas where there might be spiders. This strategy wouldn't last long. $\endgroup$
    – FluidCode
    Mar 8, 2023 at 15:07
  • $\begingroup$ While humans are indeed very good at making species go extinct, this is not the case for every species. Viruses do a lot of harm to us, we can't eliminate them. Things like mosquitoes do plenty of harm to us, we couldn't eliminate them (trying to do that would likely be a terrible idea anyway, screwing with the ecosystem in that way could lead to disastrous chain reaction that create more problems for us in the long run). Rats, cockroaches and other pests have been annoying us for most of our history, we never came anywhere close to being able to eliminate them. $\endgroup$ Mar 8, 2023 at 15:40
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    $\begingroup$ @GiantSpaceHamster The species you mention are small, extremely numerous and they hide efficiently in inaccessible burrows and cracks, or in the case of viruses, inside our bodies. Foot-long spiders that rely on fruit to reproduce can't be as ubiquitous as mosquitoes, and if they attack people they will be very visible and vulnerable to countermeasures. $\endgroup$
    – Cloudberry
    Mar 8, 2023 at 19:29
  • $\begingroup$ Perhaps the spider wouldn't thrive in the wild, but it might become very widespread in research labs as creepy CIA types and volcano-island villains mess with the mind control venom. $\endgroup$
    – Dast
    Mar 9, 2023 at 13:07

True jumping spiders are araneomorph spiders, which has certain consequences for their biology.

Araneomorph spiders' fangs point toward each-other, allowing a powerful but shallow bite, that on larger prey would tend to pinch up a small part of the prey's skin rather than making a deep bite. Unless this spider was considerably larger than suggested, it wouldn't have a sufficiently large bite to be able to penetrate a human skull - its fangs would just graze off and envenomate the scalp.

Araneomorph spiders live for only a single year, which limits their maximum size to much less than that of 'a medium-sized hat'. All of the world's largest spiders are mygalomorph spiders, which live for multiple years and can attain larger sizes, though none achieve the required size.

So, an Araneomorph spider of the family Salticidae would be unable to achieve the necessary size, and even if it could, it could not penetrate a human skull.

If we presume that "jumping spider" does not mean an Araneomorph spider of the family Salticidae, but instead means merely 'a spider that can jump', we could have this spider be a mygalomorph which could achieve the necessary size.

However, Mygalomorph spiders fangs face downwards, and while the fangs may grow to the size and apparent orientation necessary to penetrate a human's skull, the spiders would lack the necessary strength to drive them through that much bone. Because the fangs face downwards and not inwards, the spiders must use a tactic of rearing and plunging to drive their fangs into their target, that relies on the sharpness of the fangs and the weight of the spider to penetrate the target. It would not be possible for a hat-sized spider to drive its fangs all the way through the bone of a human skull with its body weight alone, and it would not be practical for it to attempt to repeatedly attack the same spot to attempt to drive its fangs through with repeated blows.

Now, assuming that despite the biology of non-GMO spiders, we could have a spider capable of leaping onto a human head and injecting a substance through a human skull into the brain, we then run into the problem that venoms typically kill or paralyse, they do not 'control the host like Ratatouille from the movie', unless we venture into the realm of magic.

Even if we assume that there is a spider capable of biting through a human skull and magically controlling it, as Trioxidane has posted, unaffected humans would quickly notice and exterminate these spiders with extreme prejudice, and potentially include their hosts in that programme of extermination.

Hence, the answer to the question is:

It's really not very practical or even feasible at all.


Same likelihood as all other animals larger than the head of a pin that specialize in killing humans. Zero.

Humans are not safe targets in the best of circumstances. All the animals that specialize in preying on us either do so in ways that don't permanently harm us, are too tiny to easily notice, or most often, both. And even then, being a louse or one of the types of mosquitoes that specialize in humans is a very hard life.

But, it could be a fun monster of the week type thing! It would never survive long term, but it could cause some serious chaos in a small town for the month or so before the species is eradicated


Why have a antagonistic relationship?

Two book series come to mind - the children of time, with genetically/nanotech modified (I forget) spiders which form complex societies and eventually ally with a 'post apocalyptic' human culture that's recovered some tech and others. The other is the Honor Harrington Series and its sphynx cats.

I think there's a few things to consider - I suspect giant mind controlling spiders would probably be wiped out pretty quickly. A symbiotic relationship makes more sense - maybe sitting on the human 'host's head allows for communication. They might communicate via 'vocal' language, with the spider 'feeling' human speech through her legs, and the human feeling spider vibrations or taps. Or psychic spiders - which take control of humans with permission and are long lived or can pass on skills, so a human can 'learn' a task with the right spider on their head. They could also be a way to communicate silently or across distances.

As for the fruit - maybe its a valuble produce, with both human and arachnids benefitting from it, and needing both to thrive. Humans have better agriculture, and an aracnid species which co-evolved and relies on a specific plant to survive might play a part in its ecosystem. Maybe they were co-developed by some made scientists.

Something that comes to mind is the dodo tree apocryphally they relied on dodos to germinate. Maybe the process of laying eggs in the fruit of this specific plant allows more reliable germination of the seeds for planting. The Arachnids on the other hand know which fruit are ripe (or even poisonous, and not good eatin), and in exchange for protection of their eggs and such work with the humans.

  • $\begingroup$ Good point! It's much easier to maintain a symbiotic relationship than a parasitic one, and I actually have a bit of a pet theory that most parasitic relationships probably start out more symbiotic. $\endgroup$
    – user102593
    Mar 9, 2023 at 5:24

Frame challenge:

Make these spiders more similar to cats.

If these spiders behaved similar to cats:

  • Eating mice, insects, etc, (large bonus if it is things people don;'t want around)
  • Don't poop all over the place
  • Somewhat social.
  • Bite/attack avoidance of humans

People would start considering them as pets, and help provide them with food, shelter, protection. This would be done by their own choice, so the whole pitchfork and torch scenario isn't triggered.

I can imagine a person waking up to seeing their pet spider noshing on a scorpion declaring "who's a good boy!, who's a good boy!"


It should probably be much smaller (probably about 2-4in) and attack while the host is asleep when the host shouldn't fight. It also shouldn't try to bite strait through the skull because its completely implausible, the bone's to strong. It should most likely attack in numbers each going to a different place on the body where they communicate, with thin webs or vibrations or some other way, with each other for collaboration of moving the body. To move the body they could use electric shocks or inject a chemical that temporarily activates the muscles in that area. At the head of the host, one would most likely bite in the back at the base of the skull and inject a chemical that keeps the host asleep while the spiders work. To the person they might have nightmares as a side-effect and wake up in a new place and could be written off as sleepwalking. The spiders would have a longer run at life, especially if they avoid other humans while controlling the host. To be possible one should be on top of the host's head to steer the other spiders, which is probably why it looked like it was controlling through the skull and and being a foot long/big is most likely an exaggeration


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