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Post by kwm2 » Sat Jul 11, 2020 2:35 pm

I’m new to this group. I ran across it while searching online for info about wild marine hermit crabs I have seen in SW Florida, in particular, the giant red hermit crab, Petrochirus diogenes, but I suppose my question applies to other species as well. I have been under the impression that a hermit crab upgrades to a larger shell when it has outgrown its current shell. But I also understand that any crab can only grow for a short period after it has shed its exoskeleton, during molting. Does it molt and grow within its current shell? If so, where does it’s cast off exoskeleton go? Alternatively, does it exit its current shell, molt and grow while buried in sand, then when the new exoskeleton is hard does it look for a suitably larger shell? This latter scenario doesn’t seem consistent with what I’ve read about a hermit crab exiting it’s shell only to quickly find and enter a new shell, often competing with other crabs to find a suitable shell. If a crab can only grow during the molting process, outside a shell, then how does it outgrow its current shell while still inside? I appreciate any help you might be able to provide, including suggestions about resources where I might learn more about hermit crab life history Thanks.

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Re: molting

Post by JoeHermits » Sat Jul 11, 2020 5:52 pm

Hermit crabs don’t leave their shells to molt. Since only the front half of their bodies have an exoskeleton, they are able to slip right out of it like a glove while still in their shells.

The cast exo is usually eaten to regain lost nutrients, so you may not always find it.

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