Here’s a video of them in action!

The video!!!!

made me think of this anecdote from 1845 :

“Our friend Bakunin is also very interested in the hermit crabs  that are found by the hundreds in each cove. In his room, he installed  in a few basins a whole collection of shells of different species, all  inhabited by these parasitic molluscs, and he now studies with passion  the manners and habits of these curious creatures who are also at ease  in their borrowing shells than other snails in the home which is their  work. He concluded from this that communism finds full justification in  the natural order of things, and that men, whose aptitudes would present  some analogy with those of hermit crabs, have perfectly the right to  claim the houses of others, as if they were theirs: one of the essential  features of the character of this man is precisely this envy which  pushes him to desire to possess what already belongs to others, and,  because of this, he makes us recognize that communism must be claimed as  indispensable for the human race as a whole. But to come back to the  hermit crabs, we really could not require that creatures, like them with  such a soft abdomen, can expose themselves, without protecting it, to  the perils of the sea: this obligation gives them the right to steal  their shell from the shells and to settle there. However, I must not  forget to say that Bakunin’s psychological studies on hermit crabs have  established that these gentlemen leave their accommodation at night and  go free to go outside.

The day before yesterday, some of these nocturnal walkers had a very unpleasant adventure. While they were away from their homes, a few younger comrades had quietly settled in the more spacious abandoned shells, and when the owners wanted to reoccupy them at daybreak, the usurpers defended themselves so valiantly against the legitimate owners that the besiegers had to withdraw empty-handed. During the night, Bakunin had heard a horrible noise in the basin and, in the morning, he found the two expellees who were camping naked in front of the accommodation they had been left with, but which were far too narrow for them to be able to install there. Bakunin assured me that the wretches, turning their dark green eyes to him, had looked at him with a melancholy air, and that he had been on the point, on several occasions, of having them reinstate the old shells of which they were the legitimate owners. But, on the other hand, it came back to him some doubts, apparently well founded, on the alleged rights of the expellees and he behaved quite like Louis-Philippe and Metternich: he considered the affair as “Fait accompli” and maintained the “status quo”. The deportees took their mishap so seriously that they died the same day, which relieved Bakunin of great weight no longer having to take care of their legitimate rights.”

-Bakunin at the beach