I'm working on a Space Opera novel featuring a group of aliens that call themselves Species 0001. Here's what you need to know about them:

  • They are a species of squid-like aliens that evolved on a water world. Their skin can be practically any color under the sun. They are very small, small enough to be held in the palm of your hand. They also have a beak-like sheath that shelters muscular neuron tendrils. (more on those in a bit)
  • They're neural parasites that burrow into the host's neck and wrap their tentacles around the host's spinal cord before unsheathing their neuron tendrils and connecting them to the host's brain and nervous system. Any sentient species large enough to accommodate them and has a brain and a centralized nervous system can become a host.
  • They are split between two groups; the Originals/Parasites who completely hijack the host's nervous system and see nothing wrong with their parasitic existence and the Altered/Symbiotes who have resolved to be better and genetically altered themselves so they give their host just as much control over the body as they do. In the former case, the host is fully conscious and effectively trapped in their own body. In the latter case, the host is also conscious, and both the alien and the host can control the body via the nervous system. This allows for multitasking, in which the host types in a code with one hand while the alien uses the other to fend off attackers with a weapon. When conflicting commands are sent, the body simply doesn't follow either until the commands change to not be contradictory.
  • The Symbiotes are persecuted by the Parasites on the basis that they "make a mockery of our way of life", and there are about 50 times more Parasites than there are Symbiotes. The Parasites are engaged in a concentrated effort to wipe the Symbiotes out and have forced them into hiding.
  • Their society is highly stratified and based on certain abilities some of them have. The peasantry have no ability, the engineers and soldiers can manipulate electromagnetic fields, and the nobility and royalty can manipulate gravitational fields. These powers are fairly weak when the alien is outside the host, but become more powerful when it has implanted itself in a host.
  • They are incredibly advanced. Almost everything they make aside from their FTL drives is composed of a collection of billions of nanobots called programmable matter, including their clothes, weapons, and spacefaring vessels. When it comes to weaponry, they use directed plasma weapons that can incapacitate or kill at the user's option in conflict with other species, but the noble class doesn't generally carry those kinds of weapons. When conflicts break out between the noble classes, they use shapeshifting melee weapons composed of programmable matter.
  • The parasites are well-traveled, and notorious colonialists, having conquered many different habitable worlds, dominating and feeding off of the planets they conquer. They noticed earth in the 1940s, and have been abducting humans since, implanting some and returning others in order to gauge how we will respond to aliens. They think they have a pretty good idea of how we'll respond now and are preparing for a full-on invasion. Fortunately, they're taking a while to prepare for this; their world domination plans operate on a 'slow and steady wins the race' mindset.
  • The symbiotes are also interested in Earth, though for different reasons. Earth is much more advanced than some of the other worlds the aliens have encountered so far and may be able to fend the parasites off if warned.
  • Their FTL drive works by creating a 'chasm' in the space-time fabric in front of the ship, then lifting the ship off the space-time fabric for a second, allowing it to 'hop' to the other side of the chasm, thereby crossing HUGE distances without technically breaking the light-speed barrier.

I'd like the novel to be somewhat sci-fi with at least some degree of scientific plausibility, but I don't need to get into a ridiculous level of detail as to physics, biology, evolution and whatnot. Note that in the world, the only planets that support life aren't too far away from earth, and thus aliens often develop along similar lines despite being light-years apart due to convergent evolution.

I'm basically asking if this is all somewhat feasible. If not, I'd like to know what parts are infeasible and how I can make them make more sense.

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    $\begingroup$ The rule of thumb for any questions regarding the feasibility of biological manipulation of DNA by aliens is a resounding "no", since humans will share more genes with a palm tree (over a half of the genome, in fact) than with any alien. If you want it, you'll need to either handwave it or not think about plausibility at all. $\endgroup$ Mar 11, 2022 at 18:14
  • $\begingroup$ Please don't edit a question to change its focus after answers have been posted. Instead, post a new question. $\endgroup$
    – Monty Wild
    Mar 12, 2022 at 23:35
  • $\begingroup$ Its been done already you should read Robert Heinlein's "The Puppet Masters'. Squid like alien parasites that embed themselves like ticks into the human central nervous system and draw nutrients from victims body. Once embedded the host has no control over their body unless the parasite chooses so (almost never happens) or it is removed. $\endgroup$
    – Mon
    Mar 13, 2022 at 0:06
  • $\begingroup$ What is a "feasible"? $\endgroup$
    – Daron
    Mar 13, 2022 at 15:54
  • $\begingroup$ ". . . in which the host types in a code with one hand while the alien uses the other to fend off attackers with a weapon." What does this mean? What is this code you speak of? $\endgroup$
    – Daron
    Mar 13, 2022 at 15:58

4 Answers 4


First, I am glad more people appreciate the amazing potential of the cephalopod class in symbiotic relations, and I think your concept paints a very good moral dilemma. I have a couple concerns with this implementation, however:

  1. Host Genetic Alteration. This sounds like an irreversible condition, and leaves open the tragic circumstance that one symbiote or parasite dies or leaves while the host is still dependant on them. If the DNA has been fundamentally altered, can the host possibly retain a fully normal life if the symbiote/parasite detach? I struggle to believe there would not be lasting symptoms of the altered genetic code (specifically related to reproduction). As scientifically troublesome it is to believe an organism's genetic makeup can be altered by another organism at all (though many stories do it), at least allow us to believe the process takes some time. But now if we add that the host is restored when the symbiote/parasite detaches, where does that process time come from? A parasite that dies, or is torn away in an accident, does not have a chance to restore the genetic makeup of the host, so I would struggle to believe it happened. So altering host DNA opens up these cans of worms, and leaves us wondering what the poor host suffers when the symbiote/parasite leaves unexpectedly.
  2. I feel many people will die crossing the street or driving a car due to the "consensus clause" of the symbiote contract. "When conflicting commands are sent, the body simply doesn't follow either." This is a bad recipe in a world full of fast moving metal objects, vicious predators, and fleet-footed prey. A deer with this symbiote will be easily killed by a mountain lion. A wolf with this symbiote will starve before catching the hare. A school bus driver with this symbiote... I will just leave that one to your imagination. This consensus contract is a crippling disability to any sentient creature, and when the host is in danger, then the symbiote is in danger. Natural selection has some plans for your little cephalopods that are not pretty at all. Welcome to the bottom of the food chain everywhere you go. I really think this problem has been handled best by the Star Trek trill species, as a voluntary contract. Your parasite class have no concerns here, they are simply body snatchers. Pure and vile criminals that the audience can universally hate. You will struggle making the symbiotes into the good guys with this contract.
  3. All of the programmable matter and FTL and scheme plotting is extraneous to the question and should be moved to their own questions. It takes away from the focus on this alien species in general.

And the squid shall inherit the earth!

  • $\begingroup$ 1: You're right. The integration is basically irreversible. Their systems are separate enough that the alien can suffer brain death without killing the host too, but if the alien abandons his host, they die. There are surgical procedures that can reverse it, but they are very hard to pull off even with the alien's advanced technology, and straight-up impossible with our modern medical technology. This is why Symbiotes consider Informed Consent, that their host knows what they're getting into and agrees to it, to be absolutely essential. $\endgroup$
    – Brinstar77
    Mar 11, 2022 at 16:24
  • $\begingroup$ 2: Yes, a few problems might arise there. But the humans and Symbiotes intrinsically share emotions, thoughts, and feelings. As a result, conflicts are typically rare, and when they do occur, they happen at the speed of thought. This isn't instantaneous, but it's close. $\endgroup$
    – Brinstar77
    Mar 11, 2022 at 16:25
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    $\begingroup$ @Brinstar77 I don't think we needed that reminder, you made it plain in the description. We get the concept of "a higher cause." $\endgroup$
    – Vogon Poet
    Mar 11, 2022 at 16:33
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    $\begingroup$ @Brinstar77 you understand that the word "sentient" does not limit your problem to humans, right? Cats, manta rays, and tortoises are eligible for your symbiotes the way you worded this. $\endgroup$
    – Vogon Poet
    Mar 11, 2022 at 16:40
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    $\begingroup$ @Brinstar77 please be careful, you can not make existing answers invalid when you edit. I suggest you simply change why they choose their hosts rather than their ability to choose a host. The word "sentient" is somewhat locked in at this point because people have gone through the effort of writing an answer. $\endgroup$
    – Vogon Poet
    Mar 11, 2022 at 16:55

Unfortunately, these beings are not plausible.

Parasitism is your problem. Parasites and their hosts evolve together, and saying that 'Any sentient species large enough to accommodate them and has a brain and a centralized nervous system can become a host' is pure fantasy. If they didn't evolve alongside their host species or a sufficiently related species, the odds of successful parasitism approaches zero, and that's just for potential hosts that evolved on their home world. A sentient species from another world? Not a chance.

Of course, if this is space-fantasy, like Star Wars/Trek/gate, alien space magic may allow this and the other magic that they do, but for any sort of reasonably hard science fiction, this, and manipulation of electromagnetic or gravitic fields is a bit unbelievable too.

Convergent evolution on alien worlds has some grounding in the realities of physics, chemistry and xenobiology, but I wouldn't expect anything that could be mistaken for a terrestrial life form except by the very young/uneducated. That trope is usually thrown around in visual media where the budget to produce believably alien biomes doesn't exist.

  • $\begingroup$ Yeah, this is space fantasy, with a passing nod at scientific plausibility. Just in case this changes the answer, I'm assuming that the only planets that support life aren't too far away from earth, and thus aliens often develop along similar lines despite being light-years apart due to convergent evolution. As a result, sentient species on other worlds ended up with similar brain structures due to natural selection. $\endgroup$
    – Brinstar77
    Mar 11, 2022 at 14:23
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    $\begingroup$ As a biologist, I have to try really hard to suspend my disbelief at this type of universal parasitism. If you want to have any sort of nod at scientific plausibility, that has to be the first thing to go IMO. $\endgroup$
    – Monty Wild
    Mar 11, 2022 at 14:50
  • $\begingroup$ Ok, how about this; The aliens can't interface with the nervous system right away, so they alter the DNA of the hosts first, during the implantation process, so that they can accommodate the alien. $\endgroup$
    – Brinstar77
    Mar 11, 2022 at 15:34
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    $\begingroup$ So, they'd just casually analyse an alien species, figure out what it uses as genetic material, how it uses it, what it all does, and then how to modify it so that the potential host produces the correct environment, which may involve producing sugars and amino acids of the opposite chirality, as well as completely alien molecules without compromising the host's health or just killing it outright? That's even less likely. $\endgroup$
    – Monty Wild
    Mar 11, 2022 at 15:39
  • $\begingroup$ Again, these guys are VERY advanced. They're a solidly Type-1 civilization, and has begun to drift into Type-2 territory with solar mirrors that harness their sun's power. Complex biological and genetic alterations to themselves and others are definitely within their power. But you are right; it is hard to introduce alien substances into the host without compromising the host's health or killing them outright. I imagine during this initial stage when they're trying to 'crack' a host specie's genome, there are countless failures that die at best, and must be put out of their misery at worst. $\endgroup$
    – Brinstar77
    Mar 11, 2022 at 15:45

Any sentient species large enough to accommodate them and has a brain and a centralized nervous system can become a host

This is the part I don't really find plausible. Parasite-host or symbiota-host realtionships are more often than not very specific for the host species. Some exceptions are ticks and the Malaria amoeba, and those basically only use their hosts as a feeder. The closest thing to your aliens that comes to my mind is the insect-parasite fungi, but as far as I know, these are specific for a small subset of all ant species.

Different planets, different conditions -> different organisms. Even though, according your rules, every possible host species has a central nervous system, there could be still huge differences among these species. Just consider these: where does an alien creature live? How many limbs does it have? How does it sense the world around it? All these change the physiology of the nervous system. Take, for example, the differences between a killer whale, a human and a vulture; and these even live on the same planet!

Two suggestions, how to fix this:

1, The Ancients (your aliens reminded me of the goa'ulds from Stargate anyway): All the humanoids/animals in the Universe have a common origin and thus a similar nervous system

2, Close Encounters of the Third Kind: Your aliens need to kidnap some members of a species first, "crack" their nervous system and only after this can they infect the members of that species.

  • $\begingroup$ I go for a mix of both. In the universe, all sentient life came from earth-like planets, and thus developed along similar lines. However, this isn't quite enough to overcome biological differences, so the aliens introduce new DNA into their host to help bridge the biological gap. $\endgroup$
    – Brinstar77
    Mar 11, 2022 at 15:26

Of Course Not.

Your aliens have a half dozen features that are completely unlike anything on Earth or known to modern science. Let's see:

  1. Tiny creatures with human-like intelligence

  2. Injects tendrils into host's neural system.

  3. Can take over any animal. In particular can take over animals from other planets.

  4. Animal that can manipulate electromagnetic fields and gravitational fields.

  5. Nanobots.

  6. FTL drives.

Any one of these stretches plausibility. All of them at once is just silly.

I suggest you drop the idea of scientific plausibility. Or lampshade-hang it like Futurama:

Farnsworth: These are the dark matter engines I invented. They allow my starship to travel between galaxies in mere hours.

Cubert: That's impossible. You can't go faster than the speed of light.

Farnsworth: Of course not. That's why scientists increased the speed of light in 2208.


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