Since a lot of people are already asking about multiple-headed creatures, I wonder what about multiple tails? Such as kyuubi, nekomata, etc. (I know some have asked about these mythical creatures, but so far I don't see anyone bringing the topic about multiple tails).

What are the benefit and cons for a creature with multiple tails (at least more than two tails)? In biology's point of view, especially to mammalian and reptile types?

Will it at least help the animal keep balance or will it make it worse? And how many tails can a creature have based on their body size?

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    $\begingroup$ Why touch one fluffy tail, when you can touch multiple? $\endgroup$ – Euphoric Sep 20 '19 at 7:36

One potential use could be to create a flexible, spread-out surface for flying or swimming. Birds and aquatic animals have wide, flat tails for this purpose, but these flat tails are generally inflexible, capable of only a single point of articulation. Multiple tails with skin stretched between them would be more flexible and add an extra degree of maneuverability.

As an analogous example, bats are more agile than birds because their wings consist of multiple fingers, adding extra points that the wing can bend and fold. Birds never evolved this because their wing evolved from an arm, not a hand. It is very rare for evolution to add a new limb even when it would be beneficial, especially for something as precisely built as a wing.

Multiple tails could also be spread out like a peacock's tail to attract mates, but this is unlikely to be beneficial enough to appear on its own.

Multiple tails would not provide much extra control for a non-flying animal. Animals that use their tails for control while jumping use them as counterweights; there is no extra benefit for using multiple counterweights as opposed to simply increasing the weight of the single tail. If you want a non-flier, non-swimmer to have multiple tails, perhaps it evolved from a flying or swimming species and re-adapted for land, keeping the multiple tails for attracting mates.

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    $\begingroup$ I like the evolved from a swimmer idea, perhaps a cephalopod that became more of a land amphibian? I know it's a bit of a lovecraftian shift away from anime, but I'm envisioning a gecko whose four "cute" tails are actually its hunting weapons . . . oh, and it kept the octopus camo ability and intellect. $\endgroup$ – HA Harvey Sep 19 '19 at 6:56
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    $\begingroup$ Multiple counterweights could in theory make it easier to retain one's balance on unstable or difficult footing, by allowing more fine-tuned adjustment than a single tail would. Think about it like trying to keep your balance by holding out two arms, as opposed to one. You're right that this isn't as much of a benefit as the advantages for flying/swimming, though. $\endgroup$ – Justin Time - Reinstate Monica Sep 20 '19 at 20:40

Some birds have their tail feathers set in such a way that they seem to have double tails.

Swallow-tailed kite:

enter image description here

Barn swallow:

enter image description here

Long-trained Nightjar:

enter image description here enter image description here

Evolution tends to weed out traits that are deleterious, so these tails either help them thrive or in the very least don't interfere with survival. At least in the nightjar's case they could make the bird easier to catch, so there must be a benefit in it to balance things out.

A true double-tailed bird could evolve so as to have very fine control on each tail, making them more agile in flight.

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    $\begingroup$ The last image suggests sexual selection which does often compromise survival in favour of some accentuated feature or ability to increase reproductive chances. $\endgroup$ – Separatrix Sep 19 '19 at 13:21
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    $\begingroup$ @Separatrix It goes something along the lines of "Look at me, I'm so strong and agile that I can survive even with these clear handicaps. Will you have my children?" I don't know that the animals are that conscious about it, but it's one reason why sexual selection can fly right in the face of any other facet of natural selection, such as predator avoidance and sustenance. $\endgroup$ – Arthur Sep 20 '19 at 6:52

In my opinion, there isn't much benefit from having more than 1 tail. The issue is that almost all animal tails extend off the base of the spine. This essentially gives some animals an additional 5th limb, which they can use to grab onto thing (Monkeys) or balance themselves (Kangaroos or Cheetahs).

Having more tails extend out of this base wouldn't help because:

  1. Attachment Point: The tails come out of the same base area, all force produced by the tails are applied through this single point and the sum of each tails movements would cancel/add to eachother to produce a single force (aka not going to help balance better).

  2. Flexibility: The tails will likely share the same muscle groups, especilly at the base of the tail, similar to our Ring and Pinkie finger. This means that the movement of a single tail will affect the movement of the others.

  3. Reach: A tail and arm combined allow for a very long range of reach, by having the tail grab onto something then stretching out with your arms. Having multiple tails however doesn't increase the Reach as the tails are all attached to a single point.

  4. Strength: The tails all share a single attachment point and all the muscles used to control the tails will need to be attached to this point. So as the strength of each tail increases, the thickness of this area will also need to increase.

  5. Flexibility: Tails are not precision tools like your fingers/hands. Usually the muscles are concentrated into the base of the tail and movements are limited to curling up and swishing back and forth. So you might be able to hold onto a sword, but your not going to be using it to sip wine from a cup like a third arm.

In terms of thickness and strength, this will all depend on the purpose of the tail. You can see that Crocodiles and Kangaroos have incredibly thick tails which they can use to lift themselves out of the water or stand on (temporarily). Likewise, animals like the Cheetah have much more uniform and thinner tails which they can move around quickly to help balance themselves out.


Quoting from my answer here: https://worldbuilding.stackexchange.com/a/87462/21117

A tail is an extension of the spine. That means the tail bones do have part of the spinal column passing through them. If the fox's tails are actual tails, then the spine nona-furcates(?) at the base of the tails, leading to effectively nine independent limbs with associated motor and sensory functions. It also means a significantly larger processing facility and muscular structure needed to control them, which ties in with the Kitsune legend of needing a hundred years to grow each tail. A newborn with nine tails would be at a severe disadvantage due to the resources needed to develop eight additional limbs plus learning to coordinate 13 limbs at a time.

If they aren't tails, they're hairy outgrowths, like, as people above have pointed out, peacock feathers, of limited movement and only really secondary sexual characteristics. A muscle at the base pulls them up and out of the way when needed but that's it. That means that while not very mobile, they're not very heavy either, and since they grow in at about 2 cm/month, the fox will have plenty of time to adjust, much like horses do.

So, what does that mean for our fox? Firstly, in both cases the tails would develop after adulthood. In the first case, the fox would have to develop the brain power to manage nine tails, at which point it would be smart enough to not need to hunt, i.e., probably smarter than most humans. Alternately, it won't and much like other mutants will die painfully. In the second case, the fox has one true tail and eight, for want of a better word, quills. These will have to be far shorter than the true tail and will only really be used in mating displays or as intimidation. At other times, they will be tucked safely out of the way.

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    $\begingroup$ "develop the brain power to manage nine tails, at which point it would be smart enough to not need to hunt, i.e., probably smarter than most humans." - I don't follow your reasoning here. Sure, they'd need more motor control neurons, but why would that imply improved cognitive ability? The part of the brain involved in throwing a ball and the part of the brain involved in answering a test problem about the horizontal distance traveled by a an object given an initial velocity and position are very different, and being good at one doesn't imply skill at the other. $\endgroup$ – 8bittree Sep 19 '19 at 22:05
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    $\begingroup$ @8bittree: Because having an additional 8 limbs is a nutritional liability. A fox that has 9 tails and is able to thrive must have made them useful somehow. It also needs to process the additional data from 8 additional limbs in order to operate them independently. contd... $\endgroup$ – nzaman Sep 20 '19 at 7:12
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    $\begingroup$ Rather than comparing two organisms with the same number of limbs, consider a PC instead: assuming that the processor is optimised for a given build, adding eight robotic arms would require additional processing power, beyond merely the input and output controls. You need to work out where each arm needs to be compared to where it is and a control system to make the corrections in real time to get it there. All this without disrupting the normal processing work, plus the workspace required to plan out how to use those extra limbs in coordination with the existing ones at a strategic level $\endgroup$ – nzaman Sep 20 '19 at 7:15
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    $\begingroup$ Your PC example doesn't help because brains aren't made out of general purpose silicon chips that can be freely reassigned to perform wildly different tasks. Brains are made up of neurons organized into areas of relatively narrow purpose. Yes, this many-tailed fox will have extra neurons dedicated to controlling and coordinating its extra tails. But that's just it: they're dedicated to that purpose. They won't help it figure out how to use fire to smoke prey out of a burrow, or how to plant crops, or how to build and control a 13-limbed foxoid robot. $\endgroup$ – 8bittree Sep 20 '19 at 15:59
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    $\begingroup$ @8bittree: Humans took a few millennia to do that too. Don't confuse our habit of passing down knowledge with intelligence--everything we have built has been through incremental increases in knowledge over thousands of years $\endgroup$ – nzaman Sep 20 '19 at 16:07

From a biological standpoint, there isn't much benefit to extra tails other than symmetry, redundancy, or as a display. Otherwise, we'd probably have seen at least one mammal evolve an extra tail by now (after all, we've seen plenty of mammals, including ourselves, lose their tails).

Because the tail is an extension of the spine, it's a little difficult to evolve multiple tails, as it needs certain kinds of joints we haven't really seen in the animal kingdom. Since the spine sits on the line of body symmetry it's easier for it to extend through natural selection than to split. The tail connects at the body not in a ball joint, but in a vertebral joint. It is conceivable that you would need some kind of exotic ball joint to support multiple tails, or some kind of "multi-vertebral" structure. Both vertebral and ball joints are only between two bones, however, and there are very few examples of multi-bone "locus" joints in the animal kingdom, much less movable forms of these.

It is perhaps important to note, however, that a nekomata has a "forked tail," in that it connects to the body at a single point like a "Y" shape. It is a bit strange that nearly every nekomata depicted in anime and manga doesn't have the forked tail, but two independent tails. The forked form would probably be more likely to evolve than say something like a nine-tailed fox, where all of the tails connect at one point together.

From a mythological standpoint, the extra tails are a sign of the creature's power. A nine-tailed fox starts with one tail, then gains an additional tail for every 100 years it lives until it has nine, then begins losing tails for each of the next 100 years. When the fox no longer has any tails, it becomes a god.

For nekomata, the legend is that when a cat is 100 years old, it will transform into a nekomata and its tail will fork. To prevent this, sometimes Japanese cat owners would remove their tails if they began to live a long time. This robbed the cat of its power and thus its ability to become a nekomata.

In both the legend of the nekomata and the many-tailed-fox, and in the folklore surrounding them, their magical prowess and power is stored in these extra tails.


Dogs use their tails for communication. Having more tails would make their communication several times more expressive, and evolution could favour that trait in a social animal. Furthermore, artificial selection could also favour it in a pet.

You can see how cute and expressive is a three-tailed dog:

enter image description here (Credits)

Multiple tails can be advantageous for other animals which communicate by them. For example, a double tailed peacock would be impressive.

In fact, that's not very different from what has already happened with flowers under artificial selection: roses and other species got multiple layers of petals where their wild ancestors just have one.


I know of at least two series where the number of tails is proportional to their power. Naruto for example, as he gains more of the kyuubi's tails becomes stronger. There is also the manga Hyper Police and the demon fox Sakura, who is short of the full nine tails and is taken as a sign that her powers have not fully developed.

The disadvantages can be the same, by having more or less tails can have particular meaning to the creature/species. If the species normally has one tail, what would not having that tail mean, either naturally or due to an accident? Having more tails could also show other traits.


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