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My alien species is mostly "diurnal", but relies a lot on echolocation to find its way around. Although it has eyes and lives in places in which light availability isn't a problem, it's main prey item during the year is most abundant in a gallery of caves underground. For that reason (and due to its ancestral origin), the creatures rely mostly on their 4, incredibly sensitive ears (essentially a slightly toned down version of "a quiet place monster" levels of sensitivity) both to listen for potential prey as well as to echolocate its way throughout the tunnels and galleries. However, due to competition against its own species and other creatures (as well as personal aesthetic purposes), I wished for them to be able to retract their external ears to prevent damage caused by things such as bites, preferably in a way that aided in preserving their hearing by further muffling loud sounds and thus better protecting their inner ears when they're not in use.

My main issue is that I don't think there's anything similar among the the known animal species of our world, with the closest I've found being how bats can temporarily "unplug" their own sensitive ears so their powerful pulses don't cause hearing problems (which I also plan for my creature to have. Would it be truly beneficial to have external ears capable of "retracting" into a special fold of skin or even into the ear canals (like some people seem to be able to)? If possible, I'd also like to know if such a mechanism could evolve naturally.

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  • $\begingroup$ Why does the creature leave the cavesystems where it hunts, eats, lives? $\endgroup$ – dot_Sp0T Jul 4 at 14:54
  • $\begingroup$ @dot_Sp0T let's just say there's something else in the caves other than their prey, which will only attack them if they are asleep, this other creature (which I plan to ask about in the future) is the reason they can't sleep inside of the cave systems, unlike their prey, which this "something" doesn't feed on. $\endgroup$ – ProjectApex Jul 4 at 15:02
  • $\begingroup$ Snails have retractable eyes. Why not aliens with retractable ears? You just have to specify the mechanism. $\endgroup$ – chasly - reinstate Monica Jul 4 at 20:23
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A better solution might be to flatten the ears. Felines can do this somewhat already. Ears flatten down and maybe camouflaged and poof you have the equivalent of retractable ears. Muscle reflex for control.

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  • $\begingroup$ This was my thought, particularly if they had ridged skulls; the pinnae would flick back into the "valleys". $\endgroup$ – Tantalus' touch. Jul 4 at 17:59
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TLDR: Don’t use muffling or “retractable ears.” If your creature’s ear works something like humans’, using a muscle reflex within the middle ear to protect against loud noises will be much more precise.


If the purpose of a “retractable ear” would be to protect against loud noises, I would suggest something different. If high-intensity sounds have posed a threat to this creature over the course of its development, it probably would have evolved a more efficient way to weaken/block loud noises.

Let’s use the human ear as a model (although humans admittedly do not have the best ears of the animal kingdom). The outer ear consists of two primary parts: the pinna and the auditory canal. The pinna helps direct sound waves into the auditory canal, which is coated with wax to protect it from blockage by dust. Then we have the middle ear, which transmits sounds using three bones called the “hammer,” “anvil,” and “stirrup.” The stirrup is connected to a structure called the “oval window,” through which sound waves in the air are transferred into a liquid medium using a vibrating elastic membrane.

Figure from Simon Grondin’s “Psychology of Perception”

High-intensity sound waves can damage this membrane. It turns out that humans already have a mechanism for protecting against this: two muscles called the tensor tympani and the stapedius muscle, which automatically reduce the intensity of loud sounds using the acoustic reflex. I would recommend giving your creature a beefed-up (and fine-tuned) version of this reflex. This is likely to be much more precise than simply muffling loud noises.

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  • $\begingroup$ Failure of this reflex is why your ears ring more the morning after a loud concert if you were drunk. $\endgroup$ – Willk Jul 4 at 20:00
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WHY NOT?

If you're dealing with an alien, you don't need a precedent on Earth, only on the alien world. I can think of various ideas that justify this, and all you really need is evolutionary pressure. If cats can have muscles moving ears, so can your alien. If a big, wide ear is vulnerable to physical damage that ruins super-hearing, there's pressure for it to evolve.

I'd propose your alien evolved in a cold climate, and big ears gave an advantage to their ancestors hearing on cold mornings, but to keep them from being frozen off in the winter they fold up close to the head or into some sort of pouch. The fighting thing merely gives it an extra evolutionary push. The big ears could serve a secondary function of aiding in cooling during the summer. These functions are, of course, not important in insulated caves, but you'd want your "ears out", so to speak, when hunting in caves anyway.

You could even fold up these ears when hunting, once you have your prey close, in order to protect from damage.

I wouldn't rely on this as a method for protecting hearing, since the kind of noise that would hurt your hearing isn't the noise your special ears would be good at picking up. MAYBE they could fold over ear canals and protect a LITTLE like ear plugs. Or the ear functions completely differently for your alien - it's up to you.

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