So, in my process of designing humanoid/humanesque sapient aliens, I often find myself wanting to have a species which are orthostatic (upright) bipeds like humans but which nonetheless have long tails, however, I do understand that the primary use of tails (balance) would not be applicable to an upright creature. The most obvious way to explain the retention of a tail would be to say that is is prehensile (as in many monkeys) or acts as a third leg (as in kangaroos), and some would simply give up and give them a raptorial posture, but I have come up with a new idea.

Essentially, my hypothesis is as follows: A ringed tail can be used as a defensive mechanism by means of tricking predators into attacking it rather than more vital body parts (or so I understand), and, if this is true, raptoriality would not evolve in a creature with a ringed tail, because then the tail would be too vital to be used as a diversion in a raptorial case, and so, if a creature's tail were ringed it would evolve to be orthostatic, in this way retaining a tail in orthostasis without prehensility. In short, a ringed tail could be a valid defence mechanism even if it were not prehensile and even in combination with an orthostatic posture, and would, in many cases, be mutually exclusive with a raptorial posture.

Is the above hypothesis correct? Or is there a flaw or omission in my reasoning?

  • 1
    $\begingroup$ What kind of predators does this creature face? Maybe a rattle would be more efficient. $\endgroup$
    – Joachim
    Nov 3, 2023 at 21:29

1 Answer 1


tricking predators into attacking it rather than more vital body parts

While it's easy for a caterpillar to make its back look like its head, putting two big spots on it resembling two eyes, having a tail which can look like the torso of an humanoid is a totally different game: the tail should be more elaborated that just a, roughly speaking, tapered cylinder and the torso should be less prominent to be less noticeable than the disguise.

This would make the entire body plan a tad ineffective.


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