What are these things on their claws??

[GAPeach252121]

So my crabs Shelldon and Myrtle just finished their 2nd molts-in my care that is (pause for celebration 🥳) and I noticed these little appendages on both of their claws...again not sure what they are or what to call them. They have never had them before so at first I thought it was possibly substrate or moss stuck to them but in looking closer it looks almost like the month appendages of spiders or extra thick, white hair. Anyone know what these are? I looked online but only found one mention of them-a person asking reddit what they were too but on her crab they were brown and the answer She got was that these were their thumbs used to drink water, but I know that's not right. I took a few photos of them on my crabs so I hope they go through. In the first picture ( the one of Myrtle shell shopping) please make sure to zoom in bc its hard to see them, they almost look clear but it's the best photo of how thick they are. Also I should probably note that both my crabs came up from their molts ALOT harrier, and one a lot larger than the last molt. Not sure if that's relevant or not.
Thanks so much!!
-Katie, Myrtle, and Shelldon

[crabocado]

I've noticed them on mine too. It looks like a tuft of setae (hairs). I just spent a while searching and came up with nothing. I would guess it has a sensory function, but I suppose it could be some kind of grooming structure, e.g. perhaps for cleaning other appendages (e.g. antennae)? Just guesses.

[CrabbyLover77]

According to The Hermit Crab Patch, they are sensory hairs called Setae. Personally, I've always called them their little fluffs. I think it sounds better lol!

https://www.hermitcrabpatch.com/Hermit- ... -a/136.htm

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[aussieJJDude]

I've noticed them on mine too. It looks like a tuft of setae (hairs). I just spent a while searching and came up with nothing. I would guess it has a sensory function, but I suppose it could be some kind of grooming structure, e.g. perhaps for cleaning other appendages (e.g. antennae)? Just guesses.

Your guesses are pretty much correct. The setae is used mainly as a sensory organ, which acts likes touch, ears and somewhat to a lesser degree, smell/taste.