One of the main problems with creatures that they have tentacles instead of manipulating paws or hands. This isn't a big problem for developing sapience, but it is a problem for entering the realm of tool making. So I asked myself How can I have a space faring species than has tentacles but still can make tools? my solution was to make them have complex mouth parts, like a praying mantis mixed with a spider. these would be controlled like any other body part and would have the job of eating and tool making. How realistic is this mouth system on a sapient creature around the size of a dolphin(minus the tentacles)?


as to frostfyre's request here is some details of my species

  • Their torso is roughly the size of dolphin.
  • they have a total of 10 tentacles; 6 where their tail would be if they had one, and 4 along their body.
  • The tentacles along their body end in a sort of psuedo-fin.
  • their gills are along the side of their body.
  • they live in warm climates.
  • for defense they have a deadly combo of electricity(located in buds along their underbelly) and ink if the electricity fails.
  • along their back are ridges similar to a sharks.
  • their lower tentacles are very strong and would bleed very profusely if they were cut.
  • their upper tentacles are thinner but more controllable, they are the second highest area of sensory input.
  • their pseudo-fins look like a large flat claw at the end of the tentacle but it is made of cartilage and covered in skin.
  • $\begingroup$ What prevents this species from using its tentacles to develop tools? $\endgroup$ – Frostfyre Dec 10 '15 at 0:45
  • $\begingroup$ technically nothing but it is very unrealistic that they could, and I am going for 100% realistic $\endgroup$ – TrEs-2b Dec 10 '15 at 0:53
  • $\begingroup$ I consider the use of tentacles more realistic than a mouth, to be honest. $\endgroup$ – Frostfyre Dec 10 '15 at 1:08
  • $\begingroup$ @Frostfyre I don't. tentacles will be slippery, wet and slimy while the mouth arms would only be wet $\endgroup$ – TrEs-2b Dec 10 '15 at 1:09
  • $\begingroup$ Hm. I was thinking more along the lines of an octopus, which does use its tentacles to manipulate its environment. You may want to provide details for your species. $\endgroup$ – Frostfyre Dec 10 '15 at 1:11

I think the problem isn't that tentacles can't be used for tool making/using, it's that your tentacles can't be used, or at least to an extent. That gripping problem can easily be fixed by not making them slimy (I'm sure you can correct mucus secretion) or adding suction cups or gripping surfaces (like most frogs and lizards i.e. geckos).

The question wasn't about tentacles however, so I'll focus on the 'mouth arms' as I shall call them. First of all, comparing real-world creatures really helps with creature-creation, and your mantis comparison is a great example. The insect mouth has four appendages called palps, they help with manipulating food around the mouth. You want something more complicated however, so the appendages would need to be longer and have more grip, of which the palps have little.

You have two main options, arm-like appendages with some sort of claw or pseudo hand, or you could go with the whole tentacle theme and have four or more tentacles around the mouth (might as well use those four body-mounted ones honestly). The 'arms', segmented or not, would need to have more complex 'hands' if you had only two, and measly pincers if you had about four, as larger numbers means less individual work, so keep that in mind.

Another point not to be missed, is that the 'mouth arms' need to be away from the face at least by a bit, as movement and tangling of limbs can occur from bunched up appendages. Also, you probably don't want most tools anywhere near your face while using them (another reason or length).

So, just to recap:

  • long appendages for safety and general usefulness
  • keep those sharp things away from the face
  • pseudo-hand is essential, less 'fingers' on more arms
  • might as well go with tentacles with suction cups/gecko toe grip

You wanna ask yourself what limits a creature from using this method. First thing that comes to mind (for humans) is the location of the eyes, the length of the arms and fingers, the opposable thumb.

For that matter, people use their mouths for a bunch of stuff involving tool making and other env manipulation (how about a mouth+tentacle combo?), but if you're limited to mouth parts, you'll need an extremely complex bunch of them. At least two would have to extend outwards for length related manipulation, and you'll want finger-like digits on each.

Check out the Dung beetle creation of dung balls. They're also the only insect known to orient itself by the galaxy :-) https://en.wikipedia.org/wiki/Dung_beetle


Our ability to use tools is heightened by a few things, such as our opposable thumbs, fingers, wrist movement, arm movement, and shoulder movement. With rotation, abduction, extension, and flexion, we can manipulate our surroundings without necessarily having to move our whole bodies.

You could structure a sort of mouth entity to be like this. You just need more complex parts, perhaps pivot points and connections on the neck (or base) or sides of its head.

You could then add different textures that allow for a higher grip force profile. You could imagine an entity with a microscopic pilose covering like the chameleon that increases the friction with contact of objects, which would definitely help a lot.

However, I see no reason these attributes cannot also be applied to the tentacles.


Your creatures tentacles are more likely to allow tool use than a mouth. Octopuses have been seen using their tentacles to use tools. They are intelligent creatures that use nerves in the tentacles to control movement, so the brain doesn't need to decide how to grab something, just that it wants to grab something.



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