HCA: Hermit Crab Association

Can LHC hear sound?

If they cannot, why they can make sound and chirping?

I have always read that they sense and feel vibrations rather than "hearing" sound waves.

they use vibrations the get a sence of there seroundings, but im sure they have some sence of hearing

I also have read what the other two posters stated. This would mean they can't hear (feel?) anything outside of the tank because the vibrations would just bounce of the glass of the tank correct?

I've always wondered that to. Like when I play certain music in my room they seem more active than when I play other music. Maybe I'm just imagining it tohugh.

Well, if the music they become active to has a lot of bass in it, that would produce vibrations which the hermies can 'hear'.

I fourth the opinions stated above.

maybe their sense of hearing is very weak, and they mainly detect sound waves..? they always retreat into their shells when I speak loudly at the tank, but when i sing softly (yes i sometimes sing at my crabs lol) at the tat, they seem not to notice it.

They dont have an inner ear and all the biology that we do. Unfortunately, they dont even have external ear openings, so their hearing is very different to ours indeed. If you want to compare it to another animal, a snake may be a good example. They feel vibrations, primarily through the ground and this is converted to sound. It may make an interesting area of study though.

Glass would not block sound. Windows only reduce sound because there is a layer of air sandwitched between two panes.

The acoustic conductivity is proportional to the hardness of the substance. Glass would conduct sound very well, while sand sound not. Harder substances will pass the higher frequencies, while softer substances will only pass the lower frequencies (the beat).

I've read posts in the past about hermit crabs becoming active during certain music, usually music with loud bass. The vibrations either stress them out and annoy them, causing them to scramble, or perhaps the vibrations remind them of waves hitting the shore, and would actually help them to navigate towards the ocean from far away.

In all, my guess is they react to low frequencies felt through their body. Hermit crabs show much more reaction to shadow and light. They don't see like we do either; they don't have lenses to focus light into images. Their eyes just react to light levels. Think more of seeing blobs of shadow and light. When we approach, if we create a shadow, they may interpret it as a predator.

Of course my crabs now have been trained to associate the approaching shadow with feeding time. That's why we can't release our crabs back into the wild. They've been domesticated I tell ya.

That mean they can feel intense vibrations, and feel light and shade?

But I found that they do not have any reaction when I use photoflash to take photo for them.

The photoflash would provide light. I think it's the shadow that causes a "predator" reaction, rather than light. The strobe from the flash might also be quicker than their optic senses. Humans process about 60 frames per second, and flash is around 1/5 of a second. Hermit crabs might have a lower processing rate. If you shine a strong flashlight on them, sometimes you get a reaction.