Normal Post-Molting Behavior?

[S.C.]

Earlier this week I posted that my crab Dudley molted. He surfaced after 6 weeks under and I thought he looked really good. He was active, eating, and seemed fine. He's gone under again and has been down for a couple of days. He took a new shell with him. He'd been poking around the shells in the tank and I noticed his old shell was empty. By the shell count, I know he has taken a new shell with him. Is it normal for them to go under again right after molting? I'm kind of worried and would appreciate any info about if this sounds normal or if something might be wrong.

[cannm]

I've had several crabs molt and go right back under to resurface months later. Every time this happened, they were brand new crabs that went for a molt as soon as I introduced them to the tank. I figured it was their way of continuing to destress.

[S.C.]

Thank you. He was up again tonight, so maybe he just likes to be alone at times. I've only had them for a few months, so they're possibly still getting used to the new tank, like you said.

[LadyJinglyJones]

And for added (conjectural) context, your crab may simply have come from a more arid locale, where during the day temps rise & humidity drops significantly. (DeWilde, a crab-ologist, studied PPs that hid during the day in 1972, and his paper isn't too hard to find online.)

Where your crab grew up, hiding under mould or digging down during the day may have been a temp. control or water saving measure.

Or he could just be de-stressing. Or timid. Or excited to be able to dig again. We will never know the heart of a crab...
[Cue Twilight Zone theme]

[Just Jay]

Two of my crabs used to do that. Also when my larger crabs go under for a long time they will sometimes break the molt up for a few days eating and drinking water. Then back under for awhile longer. Also when everyone comes up the first few days all they want is sleep, shells, water [mainly sw but a bit of fw to] and food. The process has to be very taxing on them. Plus in the wild a lot about their "home" could change and possibly be unsafe when they come up. I assume that's why they are so reserved. Nervous and tired.

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