Changing shells

[Kermie16]

One of our newest post molter, Mike, is the only one out of 3 who has yet to change to a bigger shell since he resurfaced from his molt. So this morning, I noticed a hermie in a new shell. Turned out it was Mike! He had moved from a 5/8 in to a 3/4 in shell!! Both turbo shells which seem to be his preference. When we first got him, he was in a whale eye shell (? I think that's the name of it) and he immediately switched to a turbo! Well, I was super excited about it! Then later today he switched back to his 5/8 inch. Really weird. He is also the one who has been up roaming the tank during the daytime. Is any of this odd behavior??

[The Franckinator]

Crabs change shells a lot. You will also notice how their personalities differ in their choice of shells. Sometimes, crabs may be picky and won't change unless a specific shell is laid out. Sometimes, they'll switch back and forth. One of my newest crabs prefers his magpie over other turbos in the tank. My biggest prefers a Silver-mouth turbo that is too small and a murex over the appropriately sized Pearl turbo also in the cage. Sometimes, you may have to dip the shell in the MSW to make it smell "nice" and fishy. My biggest didn't even seem to notice the Pearl until I did that.

My biggest, Ray, also seems to be diurnal - active around 2pm or 3pm into the early night. He probably goes to sleep around 10 or 11. However, the newbie I mentioned is only active around 9 or 10, when Ray is just settling down. So, one nocturnal crab and one diurnal crab.

Interesting related story: My dad takes care of Argentinian tegus. These are beautiful lizards that can grow up to 4 (maybe 5?) feet. They also hibernate during the winter, which is when my dad brings them all inside so they won't freeze. You would think they all start going down around September or October - when it starts getting cold, right? Well, they actually vary and one of his oldest tegus begins hibernation in July and comes up early the next year.

Back to your question - I don't think it's cause for alarm and is just natural variation. Maybe Mike just doesn't like that shell 3/4" shell specifically, or maybe he's not ready to switch. Towards him being seemingly diurnal, I don't think it's weird and I've read a few posts about crabs doing that.