Hermit crabs drive off robbers by vibration
Hermit crabs are unique among crustaceans - they have a soft abdomen, not protected by a shell. Instead, crayfish use mollusk shells. The cancer lives in the sink, drags it on itself, and in case of danger hides in it entirely and closes the entrance with a claw.
Since cancer inevitably grows out of the sink over time, “houses” periodically have to be changed. If in this place there are fewer empty shells than crayfish, shells become a valuable resource, for possession of which serious competition can develop, sometimes reaching clawing.
In a new study, biologists found that one of the tools to repel potential burglars is the vibrating signal supplied by the host of the sink.
Noting that hermit crabs sometimes vibrate in their shells, the researchers set up an experiment to find out the reason for this behavior. They took an empty sink and hid a vibration source in it. Power and control were carried out over a wire several meters long. The experimenters were hiding on the beach behind an umbrella.
When the hermit crab approached the sink, people could turn on a strong vibration, a weak vibration, or not turn it on at all. It turned out that in the first case, the approaching cancer ran away almost immediately, and in the second and third it tried to turn the sink over, which was obviously the first step to capture it, including by fighting with its current owner.
Apparently, the power of vibration correlates with the size and strength of the cancer, or with the seriousness of its intentions, or with both.
You can read the details in an article published in the journal Biology Letters.