mithrax acting strangely

[mykdf]

My mitrhax (emerald) crab is acting quite strangely today. I've found him on his back on the substrate twice. When I righted him, he grabbed hold of the rock and twitched from time to time. His claws are tucked underneath him as well.

Any ideas what he's doing? Is he getting ready/trying to molt?

 

[mykdf]

no one? No one has any ideas?
He seems to be acting normally now.