HCA: Hermit Crab Association

I have a Scarlet Reef shell-hole-to-hole with an empty, and it has been locked this way for several hours.

I've watched the Red/Blue Clibanarius crabs swap shells several times now, and it's always a very quick procedure; however this would be the first Scarlet (Paguristes) to leave the shop-shell, and I can't say for sure that's what it's doing.

Anyone seen this?

Still like that this morning. You can see the bit of red between the obviously old-new shells. I put in a barnacle cluster skeleton yesterday and found him, more outside than now but still refusing to let go of that shell as I moved it out of my way. I can't get any decent video for YouTube, but the crab is actively working on something , as I can clearly see it move in that gap. Now, I'm wondering if the Paguristes, or at least this species, heavily modifies the interior of their shells like some of their land kin.

Gonna keep it updated here, if for no other reason than it provides a good record of whatever the crab is doing.

And I should note that the shell being worked on is empty; it was freshly boiled not two days ago, so the crab isn't just eating from it.

Might be securing itself someplace to molt?

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Apparently it was just taking its time switching shells. Did it within the last hour.




I see no exoskeleton, and can't imagine I missed them eating it when I glanced at the crab.

Gonna leave the old shell for a few days to see if it gets a new owner, but if not, I'll try to poke around inside it to see if it's been hollowed.

Glad to hear! Will be interesting to see of they also mod.

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Phase one concludes that the shell vacated is completely hollow. I used the 90° bent side of a metal dental pick to prod around, and once I wiggled through the initial curve, the pick rotated freely inside.

Phase two begins now, when I identify that snail species the shell grew from, acquire one, feed it to my loaches, and see if it starts hollow. It'll probably be a while before I get the snail, but I'll update this when I do.

Verr excited to find out the answer!

Beautiful crab!