What natural environmental pressures or opportunities might drive an alien ophidian species to evolve sapience and caudal tool use?


  1. The species should be lacking limbs prior to the emergence of these traits, but may develop finger-like appendages for gripping and fine manipulation.
  2. The pre-existing body plan may be a result of either terrestrial or aquatic ancestry (akin to the varanid/mosasaur hypotheses), but the species must be terrestrial in the end.
  3. The head/mouth should not be involved in using or manipulating tools, but the body itself may coil or fold to facilitate gripping and positioning.
  4. The environmental, ecological, and planetary conditions, and other physiological details (symmetry, size, dimensions, breeding strategy, diet, social structure, and so on), are otherwise plastic.


Among particular species of Earth snakes there is a phenomenon called caudal luring, in which the snake displays fine motor control over the tip of its tail to roughly mimic the motions of prey animals. This activity attracts other predators upon which the snake feeds. One such species is the spider-tailed horned viper of Iran, which has evolved a fringed tail resembling the legs of a spider:

Spider-tailed horned viper

Perhaps this is an intermediate stage on the path to tool use.


Ophidian in this context is the snake-like counterpart to humanoid and does not imply either a shared ancestry, or any other similarities, with Earth snakes or the suborder Ophidia.

Caudal meaning posterior end – the tail.

  • $\begingroup$ How did previous character designers do it? I’m thinking specifically of Sir Hiss. $\endgroup$
    – JDługosz
    Commented Sep 20, 2016 at 23:40
  • $\begingroup$ @JDługosz He just wrapped his tail around things, judging from Google Images. Fine for swinging a hammer, but not for threading a needle or using tweezers. $\endgroup$
    – rek
    Commented Sep 21, 2016 at 15:01

8 Answers 8


Our sapient, tool-using ophidian traces its ancestry back to a semi-aquatic ancestor. Essentially a sea snake, or an alien analog thereof. It sleeps in the safety of burrows on land and hunts in the sea. The oceans of this world contain life not too dissimilar from Earth’s. Invertebrate reef builders create intricate undersea structures. Analogs of molluscs crustaceans, and fish take shelter in the tubes and tunnels the alien coral affords them. Our ophidian ancestor uses its narrow body to invade these tunnels in search of this prey. The coral of this world has a higher composition of tubes which form complex networks with multiple entries and exits in each reef. Several species of coral-dweller also dig and expand the tunnels. The result is an intricate labyrinth of passages filled with food. While our snake has some success slithering into the tubes head first in the hope it will bump into a tasty morsel, the snake’s intrusion creates a pressure wave that precedes it along the submerged corridors and alerts prey to its presence. The various fish and invertebrates often flee out of the numerous other exits from the tunnel system while the snake is stuck inside.

Evolution strikes upon a creative solution. By entering the tunnel tail first and watching another exit with its head the snake tricks its prey into fleeing the safety of the tunnels right into its waiting maw. Some prey species adapt to the snake’s bluff, learning the difference between the pressure wave from the snake’s head and tail and not exiting the tunnel in response to only the tail. In response the snake’s tail thickens to more closely mimic the head and develops sensitive touch and pressure senses to help navigate the passages as well as detect prey. Over millennia the tail develops into a grasping appendage capable of grabbing stubborn prey and pulling them out of the tunnels.

Free from the size constraints of navigating the narrow tunnels the ophidian’s brain is able to expand. The ability to mentally map and memorize the interiors of the tunnel networks allows the snake to flush out prey efficiently instead of simply probing at random, as well as to predict through which tunnel exit the prey will appear.

The ophidians also gradually learn to work together. What begins as opportunistic hunting of prey flushed by another snake quickly evolves into mutually beneficial cooperation. While some snakes use their tails to flush out prey others are able to cover all of the tunnel exits allowing for entire reefs to be harvested. Intelligence, cooperation, and communication become highly beneficial traits in the fledgling ophidian social groupings. The snake’s tail appendages take on new roles as communication tools through contact as well as pressure and sight signaling.

The communities learn the layouts of the reefs in their area and begin to harvest them in rotation. By hunting as a group, cleaning out a reef, and then allowing it many days to repopulate they develop a source of renewable food. The ophidians are able to spend a larger proportion of their time out of the water due to the efficiency of hunting.

The beginnings of tool use develop when the ophidians begin plugging exits in reefs. Using their grasping tail appendages they are able to block tunnel entrances with rocks and shells allowing them to modify the reefs to their liking and further increasing the efficiency of hunting.

Another form of tool use comes in using rocks to open shell-protected prey. By finding two relatively flat rocks, placing the ill-fated mollusc between them, coiling its body around the whole sandwich, and contracting, the ophidians are able to crack the shell and harvest prey that was previously inaccessible.

With stable communities and rudimentary communication through tail touching and signaling each technique is taught to the next generation and the incremental advance of technology begins. With the advent of weaving the ophidians are able to construct baskets and traps to catch flushed prey or gather shelled molluscs. This allows live food to be transported out of the sea and kept for short periods of time in natural as well as artificial tide pools. Systems of rafts, lines, and weights continue to improve the efficiency of food harvesting. These advances free up a portion of the ophidian population to become craftsmen, leaders, and thinkers. The ophidian civilization has begun.


I love this concept, the idea of snake sapience is interesting. But to your points


The luring snake is probably a good place to start, this evolution will take a long time, but snakes have been around for a long time; so this should work.

  1. The spider tailed viper is a good place to start, perhaps we now say that a new snake replaces this one, and the spider tailed viper has to move, it keeps moving until it arrives in the Congo or the Amazon. The jungle seems to breed intelligence.
  2. When in the jungle, perhaps the snake has to work harder to find food, ambushing and luring become its sole hunting strategy and it likely will lose its venom glands.
  3. It is at this point we work on its tail, now as ridiculous as it is we have two choices here

    • Tarzan approach, my first idea was that the fringes evolve to move in order to better climb the canopy and this over a couple thousand generations leads to a prehensile tail-hand thing. But this felt like I was stretching reality. So I think the next path is more likely

    • Venus fly trap approach, Just as it sounds, first the fringes evolve muscles at the base to quickly close to trap small critters, then eventually the muscles around them become more independent of each other and eventually through more small changes until you get a hand like appendage.

Tool use

I don't imagine they would be good at this, you need two grasping appendages to make things, so you will need to replaces the jaws free form jaw with a real one, a big change that is kind of ridiculous. This or the have to rely on working together with other snakes to build this; which does help with sapience; personally I'd suggest that, but the mouth also works. As to the kind of tools, that is unpredictable because snakes have not been shown to use tools, so we cannot know what kinds of tool they would build; the sky is the limit.

  • $\begingroup$ Two points: this is an alien species, so you aren't beholden to any particular Earthly species or location (the spider-tailed horned viper and caudal luring are offered as Earth-based analogues of the alien progenitor species and behaviour); and I have to be firm on the no-mouth condition (#3). $\endgroup$
    – rek
    Commented Sep 20, 2016 at 19:26
  • $\begingroup$ @rek well, I'd still suggest a luring snake analog as a base with jungle environment as a location and if there is no mouth reasoning, I'd suggest going with a birds beaks, as crow beaks are used for tools. $\endgroup$
    – TrEs-2b
    Commented Sep 20, 2016 at 19:28
  • $\begingroup$ Did you mean a beak on the tail? Because a beak is still a mouth and on the head. $\endgroup$
    – rek
    Commented Sep 28, 2016 at 18:57
  • $\begingroup$ @rek I mean have a beak for a mouth to go with the grabbing tail $\endgroup$
    – TrEs-2b
    Commented Sep 28, 2016 at 22:10

As a radically different viewpoint, consider the Chrysopelea, or flying snake. It glides through the air by sucking in its stomach and flaring its ribs.

  • Step 1: over time, this rib flair could gradually extend; the snake would be able to flatten its body still further, meaning it could have longer flight times and more control. Longer flight, more range; more control, better precision on strike; both mean a distinct advantage, and allow the snake to grow larger, while still easily hunting.
  • Step 2: as time goes on, the area around the ribs develop better musculature, for flight control and yet-wider spread. This allows ribs to move individually; more control = better precision = longer flight time.
  • Step 3: eventually, the skin around the ribs thins; a front cut-away profile would transition from an O to an m shape, and eventually to a shape like this: /O\ Meanwhile, smaller, fixed ribs form around the organs for protection. This leaves the snake with ribbon-like wings, similar to an eel's top fin. When not in use, the ribbon-wings are wrapped around the body, adding a further layer of protection. In flight, a rapid wave motion would keep the snake airborne.
  • Step 4: until now, the wings were V-shaped, widest at the front and tapering to a point at the rear. However, 'square' wings provide more lift and better maneuverability; as time goes on, the end develops more muscles and wider wings, resulting in much better control.
  • Step 5: As the control muscles grow, our snake will begin to use the dexterous wing-ends like feet while not in flight, wrapping them around branches to climb, or wrapping prey to hold them down, which prompts the development of bone nubs or proto-claws.
  • Step 6: as the claws evolve, they become more bird-like; the jointed claws turn, becoming opposing fingers, as the snake becomes more picky about its food, able to eat select parts of prey. Additionally, the claws allow it to carry material in flight (albeit clumsily), which means it can use that material to create stronger nests.
  • Step 7: eventually, some enterprising snake realizes it can drop sticks and rocks on prey to scare, stun, or kill it, and suddenly snakes have tools.

And that is how you evolve the terrifying flying bomber-snake.

  • $\begingroup$ Evolving fingers along the thorax does not satisfy the caudal/tail-based condition, unless I've misunderstood your answer. $\endgroup$
    – rek
    Commented Sep 26, 2016 at 5:13
  • $\begingroup$ This... is true. I misunderstood the question to limit to only tail-finger(s). I will edit to fix that tomorrow, when I have time. $\endgroup$
    – ArmanX
    Commented Sep 27, 2016 at 4:27
  • $\begingroup$ Edited; that's what I get for being a front-end developer, just taking the back-end for granted... $\endgroup$
    – ArmanX
    Commented Sep 27, 2016 at 17:40

I like TrEs-2b answer in long form. For his #3 point, I can see one other way this might evolve. In various species, it is not uncommon for babies to develop extra appendages as a mutation. If a snake is born with a second tail, it now has two "lures" to use -- more tempting target. Coordinating the activity of the twin tails makes the illusion of prey even more tempting, and slowly amps the dexterity of future generations. Eventually, the snake may begin constructing the nest or mound of the prey species it mimics in order to enhance the illusion, leading to developed tool use.

Eventually you have the ultimate phobia trigger: a snake with a spider on each finger, holding a knife!

  • $\begingroup$ Those mutations tend to result in limbs and digits that are not functional $\endgroup$
    – TrEs-2b
    Commented Sep 20, 2016 at 19:26
  • 1
    $\begingroup$ Tend... but not always, and to my understanding, it's our best guess about how limbs develop in the first place -- buds and bumps that turn out to be useful and develop over time. There are cases of a sixth finger on a human being a usable finger (for example: io9.gizmodo.com/5835676/this-mans-hands-are-no-optical-illusion). It's rare, but if it does represent a breeding or survival advantage, it should catch on. $\endgroup$
    – SRM
    Commented Sep 21, 2016 at 3:15

Observation 1 Sapience life forms don't normally have advanced/powerful limbs, instead focus would be on developing a generic limb - tail in this case.

Observation 2 Tool use involves co-ordination between mind/eyes and the part of body in use - let's use tail now onwards.

Result 1 Eye of our alien snake should be able to see very easily in any direction - where the tail is using the tool. - this is very important. So, imagine a pair of eyes on top of a big head. As brain is developed the head is big and eyes are separated enough to excellent sight.

Result 2 The snake would be evolved to move backward as naturally as forward.

Result 3 The end of the tail would split at least into two or equivalent to the number of sections in the snake's brain. (I personally like to have 4 sections in the brain and tail split in to two and each ends are split into two again. - but let's not do this to avoid similarity with hand)

Tool Use While working - the snake will work backwards, moving the eyes to tail and controlling the device with two split ends. So, may be typing with tail and resting head on a special mouse/touch pad kind of thing. (Note: I am assuming that this alien spices is as evolved as humans on the Earth)

While socializing/playing - the tail has to be very agile and sensitive. It could be the body (or tail) language for the snake community.

  • $\begingroup$ This reply assumes the evolution to explain behaviour, rather than speculate on behaviour that would justify the evolution. The tail-forward movement is a very interest idea though. $\endgroup$
    – rek
    Commented Sep 28, 2016 at 19:14


We'll start with a snake that is already somewhat gregarious, similar to the US Timber Rattlesnake, but before it developed it's infamous rattle. Since snakes like these already have a modicum of social structure and are not individually territorial, they have an ability to share behaviours.

Early on, long before the first ape picked up a stick, one family of our snakes had bit of a medical problem; they had a genetic tendency towards a mild form of palsy. It wasn't severe enough to be debilitating, except when hunting. They weren't very good at sitting still, and tended to twitch a little when they tried. Often, this led to dislodging pebbles or other debris in their vicinity, giving away their location. It was an unfortunate trait, and as it spread throughout the family, it seemed likely that it would lead to them being culled from the genetic pool.


Happily, their dry, gravelly environment gave them a solution. Quite by accident, a few of the stronger snakes would actually flick rocks with their tails while convulsing, and throw pebbles far away. This would be confusing for prey species, who would detect the movement and noise as further attackers, and often led to the prey dashing straight into the snake to escape the noise of the false attacker. Other snakes learned the behaviour from their siblings. Soon enough, size and tail dexterity were selectors of successful snake populations, and the Rockchucker was established. Flattened tails, sometimes even with an indentation to facilitate scooping up a pebble, began to appear about this time.

Predators As apex predators, the venomous Rockchuckers had existed for some time without really having another species prey on them specifically. There were some pesky mammals, however, that tried to prey on unprotected nests, and it was only a matter of time before one evolved an immunity to Rockchucker venom. This was the Banded Monduck. Fast, big, and unafraid of being bitten, they were a force to be reckoned with.

By this time, though, Rockchucker evolution had also moved forward. They'd gotten somewhat bigger, and supported the appropriate brain functions for long-range binocular vision. They could now aim those rocks they at a considerable distance. Nevertheless, one snake was unlikely to take out or scare off a Monduck alone, so those Rockchucker families that stayed around their nests and defended it as a group fared considerably better than their less-gregarious counterparts. By now, the tail tip of a Rockchucker was almost prehensile, flattened and flexible enough to grasp rocks and sticks.

Bigger prey, and the first buildings

Rockchuckers continued to grow, and so did their brains. Upper ribs flared out and fused to make a secondary skull to cover this expanding grey matter. Rockchuckers could no longer burrow, but were now big enough to eat mid-sized creatures like coyotes, from whom dens could then be stolen.

The next big step came with the collecting useful things, and transporting them to a work site. Building ramparts of debris around nests was a natural start, and true fingers began to appear to support this detailed work.

Full sapience Musculature began to appear about this time that allowed both the head and the tail to stay reared up while the snake moved. In many ways, this was the defining step in their evolution to full sapience, in much the same way as human bipedalism. With the ability to carry objects by holding the tail aloft while slithering, many capabilities were enabled. In particular came the ability to collect burning bits of lightning strike and fire fuel. This enabled the cold-blooded reptiles to maintain body temperature through the night, and stave off seasonal hibernation. Crotalus Habilis is born.


Our snakes evolved from the same stock as rattlesnakes did, but instead of rattling, they developed the ability to throw rocks. This basic tool use, dominated their evolution, and favoured more and more manipulative tails. Ultimately, sapience and a snake civilization is the result.


What natural environmental pressures or opportunities might drive an alien ophidian species to evolve sapience and caudal tool use?

Regarding the possible environmental causes for sapience to evolve, it seems that for both mammals and birds that the common denominator is the existence of social life. The current thinking is that to understand and solve social interaction challenges requires adaptive brain capabilities which can then later be applied at solving practical problems (tool usage).

What could force ophidian into social life could predatory pressure. Similarly to birds which can fly in huge flocks to reduce predatory pressure, there could be a predator feeding on this ovidian which forces them to live in huge flocks to maximise their changes of survival. Being themselves predators they would then need to develop group hunting to attack big enough animals to feed them. The combination of both leading them to adapt to social life.

Tool usage has been now observed in the wild with mammals, birds, cephalopods and also reptiles. Common speculation is that toold usage comes as a byproduct of intelligence and physical traits making it easier are selected over generations. Some possible ideas include:

  • Elephant like trunk control: genetic mutation allowing the tail to grab prays away from the head and bringing them to the mouth
  • Octopus like control: a genetic mutation could duplicate the tails and allow multiple tails with 'trunk' like control capabilities (similar to polydactylie)
  • claws / finger development: a genetic mutation could turn the spider on the tail to hard keratin which at first would be able to hook preys and eventually over course of mutations could turn towards hand like fingers.

Any or all of the above changes would lead them to being able to handle tools. The actual tool selection starting most likely with sticks and stones and evolving alongside similar lines as ours.

One last comment, tool usage and stone age is not the apanage of humans so your ophidians obviously could also do it.


The evolution of caudal tool use probably wouldn't happen with snakes.

While the idea of a sentient snake with a hand on the end of its tail is interesting, it probably wouldn't evolve. Why? Because snake-like bodies are evolved to do all of the things that most animals do with limbs and appendages without them.

Consider the general reasons that appendages assist animals that evolve them: mobility, capturing prey, and manipulating the environment. Snakes have evolved a system of motion that doesn't require limbs (slithering), and which wouldn't really be aided by the development of limbs, especially at the end of the tail.

Unlike something like a scorpion or a monkey, in which the tail can be held overhead and used in a similar manner as a limb, the way that snakes move requires that their tails trail behind their body. Even for tree climbing, which drove the evolution of hands in apes, snakes move between branches by anchoring onto a tree branch by wrapping their body around it, and then extending their head to another branch.

Capturing prey follows a similar pattern in snakes. They evolved to do it very well without limbs or grasping appendages, and are unlikely to evolve a grasping appendage to help them to this. Snakes hunt by launching their heads at their prey and biting, which they've evolved to do very well. All snakes that use caudal luring are evolved to do this: they use their tail as a lure, but then use their head to capture their prey.

The last reason that appendages evolve is to manipulate the environment. Adaptations like pedipaps and chelicerae help arthropods do this, in some instances, and the trunks of elephants would be another example. However, a common theme with any appendage that helps an animal manipulate its environment is that it's an appendage that the animal can see. Tails trail behind snakes, so having a hand on the end of the snake's tail wouldn't really help it as it traverses its environment head first. A snake would have to stop moving and curl its tail forward to use it to probe the environment, an energy intensive way of doing something that it can probably do better by just using its head/nose, which is why snakes like the hognose snake have evolved heads shaped for tasks like digging.

Lastly, snakes probably wouldn't evolve complex caudal appendages because they would be easy to injure while crawling through an obstacle-ridden environment. Snakes slither with their bodies and tails on the ground (with a few exceptions like sidewinders, who don't slither most of the time). A snake with a grasping appendage would drag that appendage on the ground and through whatever sort of environment it was crawling through. This isn't a problem when that appendage is comprised of modified scales that will be replaced when the snake sheds, such as in the case of the spider-tailed viper, but a larger appendage of muscle and bone could easily become injured and infected. Snakes have evolved smooth, streamlined bodies for precisely this reason, and any adaptation of a less streamlined form is likely to be selected against.

Caudal tool use could happen, but it would probably happen in legged animals.

This isn't to say that caudal tool use couldn't evolve, just that it probably wouldn't evolve in snakes or snake-like creatures. Something like a scorpion or a spider monkey, which carries its tail in a manner which doesn't affect ordinary motion and whose tail can easily interact with objects in its field of vision, might be able to evolve caudal tool use.

Even this sort of evolution, though, would be much less likely than evolving trunks or hands to manipulate the environment. Tails, ultimately, are at the wrong end of the body to interact effectively with the head, and just about anything that a tail can do, with regards to interacting with the environment, an arm can do better.

  • $\begingroup$ I asked how it would evolve, not how likely it is. I also think limiting the possibilities of snake-like organisms to Earth snake behaviour is unnecessary. An ophidian body plan doesn't require exclusively forward-facing eyes any more than a humanoid body plan, for example. It should also be noted that when luring, snakes keep their tail in sight. $\endgroup$
    – rek
    Commented Sep 28, 2016 at 19:11

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