For those that do not know, the tardigrade is a microscopic animal that can survive:

  • extreme heat
  • extreme cold
  • extreme levels of radiation
  • lack of water indefinitely
  • lack of food indefinitely
  • and even the vacuum of space

Tardigrades can be found on every continent including Antarctica (rare for any animal).

Basically, tardigrades are the apex of survival based evolution. But can we make them sapient? Obviously the first problem is their size, but even ignoring their size (let's say they live on a world with low gravity), is it possible for an animal that matrix's like the tardigrade to be sapient?

  • $\begingroup$ Are you looking for human-like intelligence? Or bird-like? Rodent like? $\endgroup$
    – WRX
    Commented Mar 21, 2017 at 15:27
  • 2
    $\begingroup$ Part of their survival skills like drying out wouldn't be compatible with what we understand as the requirements for such a large/smart brain. $\endgroup$
    – Mormacil
    Commented Mar 21, 2017 at 15:32
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    $\begingroup$ Is "you do not" an acceptable answer for you? Also, which definition of sapience are you using? One from Wikipedia is rather unspecific. $\endgroup$
    – Mołot
    Commented Mar 21, 2017 at 15:36
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    $\begingroup$ @Mołot It's either "you do not" or "of course you can. Just use your favorite brand of handwavium". $\endgroup$
    – sphennings
    Commented Mar 21, 2017 at 15:38
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    $\begingroup$ @sphennings is right, handwavium required, and impossible within the theory of evolution as we know it, to the best of my understanding. $\endgroup$
    – Mołot
    Commented Mar 21, 2017 at 15:40

2 Answers 2


Of course, the limiting factor here is the physical size of the brain and how many cells/connections there are to make use of.

In their current size, individual intelligence is of course unfeasible.

So, you have two options:

  1. Make them larger - Doing this will involve some pretty freaky chemistry (and physics) in order to maintain their dormant (tun) state.
  2. Give them a Hive Mind - a group/swarm intelligence that interfaces and produces the end result of some sort of intelligence. It's doubtful that this could be expressed as being "sentient" in the classic understanding of the word, however.

I don't think that either option is realistically feasible.

  • 2
    $\begingroup$ Ad 1. It's not only chemistry. It's also, or even mostly, physics. Oxygen diffusion speed that allows them to give up on having lungs or blood. Uniform temperature preventing breaks from tension created by uneven heating. Fast and reasonably uniform drying and rehydrating. And probably more. $\endgroup$
    – Mołot
    Commented Mar 21, 2017 at 16:23
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    $\begingroup$ @Mołot I wrote an answer on another question, where I explained some of the problems with increasing the size of a tardigrade: worldbuilding.stackexchange.com/a/70020/31610 $\endgroup$
    – AngelPray
    Commented Mar 21, 2017 at 17:04
  • $\begingroup$ A hive mind is an excellent workaround to this problem! $\endgroup$
    – Cort Ammon
    Commented Mar 21, 2017 at 17:53
  • $\begingroup$ Gotta +1 for the hive mind. Emergent intelligence has lead to ants being the most successful species in the recent history of the planet, so a hypothetical eusocial tardigrade nest would be... Well.. Terrifyingly unstoppable. $\endgroup$
    – Joe Bloggs
    Commented Mar 22, 2017 at 11:46
  • $\begingroup$ You cannot increase their size, as this will prevent them from getting enough oxygen. There are no respiratory organs in the water bear allowing for gas exchange to take place all over the body. --> This only works for very small animals. $\endgroup$
    – fgysin
    Commented Mar 22, 2017 at 11:57

The hive mind proposed by Pete is intriguing.

I have a third alternative, stolen from Hal Clement's novel "Needle"

The creature in that book is descendent from something more virus like. It has the capability of being parasitic/mutualistic with an arbitrary host, but since the individual cells are orders of magnitude smaller the mass for an intelligent host is much smaller.

If the intelligence is on the scale of viruses, and can support the same connectivity per cell, then you need a couple trillion virus particles per tardigrade.

That said: The sensory equipment of an insect is radically different from anything you are used to. Chemical senses tend to be far more acute, and vision and hearing much more limited.

Suppose that your intelligence is an artificial life form composed of nanites. They are parasitic on tardigrades as a convenient source of energy, and mobility.

  • $\begingroup$ Symbiotitc, rather? The fused tardigradite gains intelligence which all the nanobial viri alone will lack. $\endgroup$ Commented Mar 21, 2017 at 21:31

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