I am no marine biologist, but I can almost guarantee that the hermit crabs are not fighting. I have witnessed this activity numerous times in my tank and never has the ritual lead to any kind of damage or death.
If you actually look very closely, one of the hermits will be withdrawn into its shell, and the other hermit will occassionally prod it with its claws, while vigorously fanning its maxillipeds.
During this action, at no point does the "dominant" hermit pinch the other in any way. In fact, when they do finally part ways, thier behavior goes back to normal almost instantly.
A few times when I was observing this behavior, I actally separated the two to opposite sides of the tank to see what would happen. Eventually the instigating hermit would make its way over to the very same hermit it had in the prone position and restart the ritual. This leads me to believe that the act is not random, but the hermits are actually communicating on some level.
Once again, to further clarify: in none of the cases were either of the hermit crabs harmed, and in no case did ownership of shells change.
Hermit crabs are highly social animals. They do not have a complex social order like bees or wolves; but more along the line of pidgeons or rats.
Can anybody tell what the hell are they doing lol here is a pic.
