I've also been witnessing some really strange behavior from the male who mated with most or all of the gravid females. (I can only confirm two of the females mated with Kermit, my alpha male, who I'm 99% certain used to be female two molts ago. I'm guessing, as the biggest crab in my colony she stepped into the role. It's not that uncommon in fish and certain other invertebrates and I really have no other way to explain it. She's always been the noticeably largest crab, so I didn't get her confused with another.)
Anyway, the weird behavior was similar to guarding and others in here have talked about seeing guarding behavior in males right around the time of spawning, and they assumed it was about mating, but it doesn't look like mating to me...it looks as if the male is trying to control when and/or where the female spawns.
Lola just came out of hiding (she's one I can confirm mated with Kermit) and while edging toward the saltwater pool, she climbed up the edge of the tide pool (a smaller reptile rock with shallow saltwater) and fell in. She looked relieved and kind of sat there very still...then shooting out from nearby comes Kermit and he gets in the pool right away, too, and shoves Lola out, then follows behind her, pushing her away from the pool and back into the "woodsy" area where I have lots of large wood pieces and a chia garden and leaf litter. Essentially as far away from the saltwater "beach" as one can get in my tank.
Why would the male not want the female that he fertilized to spawn? She's a very small female, probably not especially experienced at this process...could Kermit be monitoring for the best conditions? That seems so unlikely, but I'm having trouble coming up with another explanation. It was a really swift reaction, like, "What are you doing? Get out of that tide pool now!" And if Kermit used to be a female, who better to know when conditions would be right? Just sayin'.
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