A long time underground

[IamSam]

I am still fairly new to hermit crabs, I've had mine less then a year.

I'm sure both my crabs have already gone through their moult in October. They are in a room that I try to make sure stays at at least 70 degrees. They have a heat mat that honestly only bumps it up a couple degrees but with the tank insulated with cardboard and foil it gets up to mid 70s to 80.(I will be getting them a better heatmat and thermostat) and the humidity is always 80-90%. I do not mist often. I heard if your humidity is constant then it's not necessary but I could be wrong. I change their water once a week, though i used to do it twice a week.

My issue is that they have both gone underground for a long time and I'm not sure why. Charlie has been under for probably three weeks and Rodney has been down for two. Their food is untouched. I checked and looked under the tank and they are both alive. Theirs no way they could be trapped underground right? I am sure they already had their moults but I'm reluctant to dig them up.
Should I mist more? Is the temp not good for them? I recently added in a reptile net that I soaked in saltwater overnight and dried before adding. Other then that and some issues with the tank heat that I mentioned, nothing has changed.

[hermitsinnc]

Unless your crabs are super big (softball-sized), they should be molting quite often. It's not unusual for them to molt, come up for a week or two, and then go down to molt again. 2-3 weeks is not a concerning amount of time at all.

Since they eat so little, the only way to really be sure that they aren't coming up overnight is to smooth out the sand completely so you can spot tracks, or to have cameras.

There is no need to mist on a regular basis. Misting is only a temporary fix for low humidity, it's not good to do often (because of flooding).

I know it's hard to wait (mine have been down for a while now), but please don't dig them up. There's nothing drastically wrong with your tank that should cause them to stay under.

[IamSam]

They are small in like 3/4 to 1 inch shells.
How often do smaller crabs molt? I was under the impression it was like every 18 months.

[wodesorel]

Crabs that small can molt monthly, but usually it's every 2 to 3 months. Only fully grown jumbos will wait up to 18 months, but even then they tend to go yearly.

[IamSam]

Ahh, so Google got it wrong.

Thank you. This is extremely good to know.
And to think I was relieved that I wouldn't have to worry about their molt for another year. Too bad.

[Tom2433360]

I've had my crabs for 6 years, and when I first got my biggest crab (Phil, about a 1.2" shell opening), he dug underground and stayed there for 4 whole months. I thought for sure he was dead but I wanted to wait til I cleaned the tank to dig him up. It was only about a week before I was about to clean when he came up. Now I don't really question it, I just try to trust that he knows what he's doing and I don't interfere. Not sure what kinda crab stuff he's doing down there considering the actual molting process doesn't take too long, but he always comes up - maybe he just needs some alone time . One of the best things I've done is make the substrate as deep as possible (it's about a foot high now) so he can do whatever stuff he needs to do with a lot more room to do it. Good luck op! Crabs do weird things all the time and they are very misunderstood animals; Google doesn't usually help but this forum is the best place I've found for this kind of stuff.

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