"Trilateral symmetry..." Topic

Hi All,

I've been trying to learn to sculpt of late, in fits and starts. One of the things I'm working on for personal use is a trilaterally symmetric alien. E.g., a tripod with body stock and 3 arms aligned with the three legs.

That said, despite oddity like figuring out how it might actually walk ;), I started wondering, if such a creature were to develop projectile weapons, and more importantly *modern* or sci-fi projectile weapons, what would they look like?

We (bilaterally symmetrical) humans can fairly easily design various things to be held with TWO hands. Would such aliens use all three hands for their rifle equivalent? Only two? Why?

Lookin' for some ideas… fire away. :)

They would probably have no concept of "front" and "back." This would mean that their armored units would be equally armored all the way around, as opposed to our AFV's, which tend to be heavily armored in front and lightly in back.

Assuming they aren't more dexterous than we are, they'd be limited to one weapon at a time. So it would probably be a two-handed weapon, unless their arms were so long that they could easily reach halfway around themselves to get all three limbs on one weapon. Their third arm would more likely carry a shield of some kind.

Would these aliens have "handedness" -- a preference for using one limb over the other two? If yes, then their weapons would look like ours, with a preference for using them on one side of the body. If not, then their weapons would probably have no preferred side, so they could be fired by any pair of limbs at any time. This might mean that spent brass would eject downward instead of to one side, for example.

I can't see any advantage for using three limbs on one weapon, except possibly to support a heavier gun.

Sensory organs will probably cover all directions as well. I think it will take a huge leap to work designs that are not just adaptions of 2 handed weapons/tools

Maybe one weapon for each hand/tentacle, and a split brain to permit acquisition and firing by each at the same time, sort of like how chameleons can rotate their eyes to watch enemies/prey in two different directions at the same time.

I prefer this concept, since presumably they will be more formidable in battle. That gives the tri-limbed creatures a reason for existing, since they should be an improvement over bipedal creatures.

That depends on if each "side" is really the same. Since our symmetry lends itself to 6 cardinal directions (front, back, left, right, up, down), maybe theirs gives them 8 (each "face" and its reverse, plus up/down).

It's also possible that the axial "up" would be where their sensory organs and feeding oriface(s) point, and they can bring all 3 "arms" to bear to put food in, manipulate things, etc. They would orient themselves in what we would consider "horizontal", and could possibly have the "extra" set of limbs specialized for grasping. Though if they were truly symmetrical, they might just "prefer" one pair for walking and one for grasping in a way similar to our handed-ness.

Maybe 3 eyes / sets of eyes. Limited vision all over or focus them all for detailed vision in 1 area, like the crosshair eyes of the crayfish. If so, maybe 3 smaller weapons rather than 1 big 2 hander and a shield or 2 "pistols" and a shield

Phil

There would probably still be a "dominate" direction. Thinking along the lines of a starfish or the like, there is still the tendency to lead with one point. I could imaging a series of weapons and defense, particularly if the weapon(s) need to be reloaded or recharged, with a rotational tactic spinning them like a carousel to either keep each weapon on target or to alternate a two handed weapon and a shield. I can see the vehicles developing with a similar concept, rotating on the battlefield to keep a charged weapon aimed at the enemy at all times.

We (bilaterally symmetrical) humans can fairly easily design various things to be held with TWO hands. Would such aliens use all three hands for their rifle equivalent? Only two? Why?

I think the answer to this is actually pretty simple- we have two very broad classes of modern hand-held weapon- one handed (pistols) and two handed (muskets, rifles). The reason we have these two classes in each has advantages and disadvantageous- Rifles tend to have better performance but require both hands to utilize effectively due to size/weight, Pistols have less performance but are lighter and leave a hand open for other tasks (there are other pros/cons to each, obviously, these are the most pertinent to this discussion).

I presume a race with three grasping limbs would follow a similar path in that they would have three classes of weapon- one handed pistol-equivalent, two handed 'light rifle' and a three handed 'heavy rifle'. The trade off is the same- more power but less flexible as the number of required limbs increase. But there would be no reason to stop at two hands when a three handed weapon with greater performance is possible.

This doesn't deal with 'handedness', coordination and related issues, but I think the reasoning for having both two-handed AND three-handed weapons is sound.

-Will

Where does food go in, and waste come out? Where are the eyes, ears, whatever?

Those will say as much about weapons use as anything.

One limitation of two arms is having to multitask the detailed aiming and discharge hand and the reloading hand. Our 3-armed friend could dedicate one to each.

Oh, and standing is fine, but how do they go prone? Stand up again? Bend down behind a gun shield? Crawl?

One limitation of two arms is having to multitask the detailed aiming and discharge hand and the reloading hand. Our 3-armed friend could dedicate one to each.

Ah, great point. So a 'three-handed' weapons' primary advantage might be ROF rather then range/penetration/Accuracy.

-Will

Not to stir the pot (people say that when the want to make trouble). Why 3 arms and 3 legs? Why not just 6 appendages. Sometimes that act are arms and sometimes as legs. Much like a chimp. The one good scene on the new Planet of the Apes was when you see one of the apes writing and then they zoom out and she is using her feet.

Vince

@VCarter- well, limb specialization does have advantages from an evolutionary standpoint. But a creature with 6 (or more) non-specialized limbs would be perfectly possible.

-Will

So they have hands?
Do they have opposable thumps?
What was the reason to evolve a trilateral symmetry?
Why did their ancestors began to use tools?

It would be interesting to sketch out a bit more of the ecosystem. Bilateral symmetry starts pretty early in our ancestral tree; overall "segmented worm" structure even earlier. No species really exists in isolation.

Multiple eyes, like a wolf spider, which has eight of them.

spiderzrule.com/wolf.htm

Would they have a head like ours, which can only face in one direction at a time? I read a Star Trek novel recently with an alien race that had one "eye" on a frill that wrapped completely around their head, giving them 360 degree vision.

A compound eye, mounted on the top of the head could permit 360 degree vision – like a dragonfly's eye.

Why because God made them in his image…

trilateral would allow for 360 consideration of the world around the alien, I would consider three fingers/toes and even three sexes to finish the design.

so in regards to three limbs, the one in action would be the focus, so make the equipment easily handled with one limb…no preference of need for two, it is just passed along to the limb best angled for action/intent.

What about the Tripods from the BBC series:

picture

"They would probably have no concept of "front" and "back." This would mean that their armored units would be equally armored all the way around, as opposed to our AFV's, which tend to be heavily armored in front and lightly in back."

Would they also have no concept of chairs? How do they strap themselves into a shock mounting in a tank or a pilot's seat in a fighter capable of violent maneuvers? Would they ever have riding animals, and if so, how could they ride?

They could sit on stools, generally.

A shock mounting would have three prongs, to brace them in each "direction" -- forward, left and right (with no sense of "back").

Wow. Tons of feedback! :)

Couple of answers to a few questions posed…

Do they have hands and opposable thumbs?

I think I'd like to see them have three digits (hands yes), all aligned towards the center (grasping claw). So, while they would have capabilities similar to our thumbs, the "fingers" would all be the same.

For the eyes, I was considering either three eyes, one each between and above each arm set. Alternately, eyes on stalks off the top of the body could be interesting. While they likely would not have specific front/back, they might "focus" two eyes at a time, with the third acting almost like periferal vision. That would allow them to shift focus into any direction, and still be somewhat aware of what was going on in the unfocused arc. :)

How do they crawl?

I think that they don't. They can flex the legs to lower themselves to a squat, and they might be able to "duck walk" crouched, but likely don't crawl. Maybe roll if they fall over.

What was the reason for developing trilateral symmetry?

I really don't know. Mostly *my* reason was 'cause I was playing around and made an armature with three legs and three arms. :)

Why 3 legs and 3 arms? Why not 6 appendages?

Well, 'cause that's not how I'm making them. Not trying to be rude or trite.. just saying.

Again, thanks for the ideas and insights. If this turns out, maybe I'll try making 1, 2 and 3 "handed" weapons for them.

Thanks!

Hmmm…sorta like the RAMA series ?

Couple of novels to look at: On Basilisk Station by David Weber (available as a FREE download from Baen Books) has 'natives' with multiple upper limbs.

Her Majesties Bucketeers – can't remember the author – has tri-sexual starfish like 'aliens' with a sophisticated society and military tech at 3 Musketeers level.

"Thinking along the lines of a starfish"

Starfish aren't technically radial creatures; they grow from bilateral larvae…

Internally they actually resemble a worm bent round into a loop. They use the same genetics to govern limb placement along that bodyplan as insects and humans do (it seems to have originated very early in evolution; almost all animals share it) -- and it's all oriented around distance along a body. Starfish have, basically a front arm, 3 more and then a back arm arranged in a ring. The arms are actually slightly different sizes as the starfish grows. If you insert extra bodyplan genes, it will grow extra limbs. Six-armed starfish have been caught in the wild.

There's a radially symmetric species in the sci-fi novel "Calculating God"; it has (IIRC) four arms space around the body and a 360 degree vision system wrapped around the head.

One thing to consider is that in Earth's ecosystem, a lack of ability to focus attention in a given direction and particularly to not have strong forward binocular vision is characteristic of prey animals rather than hunters.

Oddly, if you go back far enough in the fossil record, such creatures were common here.

An alien race contest in Space Gamer many years ago produced a trilateral race that "spun" instead of walking like we do. Each foot had enough rotational ability at the ankle to allow them to "spin" in a straight line. A "run" was almost blurry in rotation speed. Their brains and senses were tuned to rotational movement, and they were deadly with "thrown momentum" weaponry like spears.

Not sure if they worked up an SF experience for them or if they were strictly a fantasy race.

Recently I have been sketching, doodling and otherwise brainstorming on ideas for non-humanoid, sentient aliens. One of the ideas I came up with was along the lines of the starfish idea too.

In the case of the race I drew up, each "arm" was in fact a trunk terminating in a full set of sensory organs and a set of manipulator tendrils. This gave the alien no "front" as we know it and the ability to react in pretty much any direction.

-Eli

There can also be cases of species starting as radially symetric and being pushed away from it by later development.

Traveller's Hivers are a case of radial hexapodal symmetry moving toward a vague bilateral symmetry. They are six-limbed starfish with only two diverging features. One limb has specialized into a sensory cluster and the opposite limb has specialized for reproduction.

Well, you guys are doing pretty well – great ideas and some logical approaches. My zoology degrees seem to be unnecessasary here; Love to see any sketches/minis that come out of this . . . :)

OK, one point: Blackscribe, there are existing three-part creatures and radially symetrical lifeforms all over the planet. Mostly non-chordates and coelentarates today, and they just might outnumber the bilaterals by a fair percentage as well.

Covert Walrus,

Assuming the "dolly" I'm working on now comes out OK, I'll see if I can kit it out into a small line, likely to be sold (maybe by me directly, maybe elsewhere) I'd give it at least 2 months though. I only sculpt periodically and it takes me forever to finish things. :)

Lerchey,

Keep us posted. If you sell it to another manufacturer, make sure you let us know (if they are okay with that).

-Eli

The creature described as 3 legged and 3 armed sounds alot like a STARFLEET BATTLES Hydran.

Thought the Hydran were the lizard/fish guys and the three legged three armed guys were the Edoans from the Star Trek animated series?