How hermit crabs get rid of their shells | Science

Scientists have discovered that hermit crabs are shaking in their shells to keep their competitors away from their plans.

Field trials conducted on a Costa Rican beach have shown that hermit crabs are quickly deterred from expelling an incumbent operator when they detect strong vibrations from the sea. ; inside.

Researchers at Dartmouth College, New Hampshire, began to study the role of vibration after observing that land crabs maneuvered when others climbed onto their backs.

The competition for desirable shells is so intense among hermit crabs that animals do not hesitate to climb on those they pbad to determine if they are able to chase the current owner. Most only climb the ladder of the property when another crab dies or is expelled.

"They are constantly trying to find out who is weak enough to remove them and go into this shell," said Mark Laidre, who is studying the social life of hermit crabs. "When someone jumps on them, they hide inside their shells and perform that maneuver to dissuade them."

The sudden movement is not enough to dismiss an abuser, but the experiments of Laidre and his colleague Louise Roberts suggest that by waving the hull, the crabs report that someone is at home and has the same. intend to stay put.

During a series of field tests, Laidre and Roberts observed the hermit crab approaching a particularly well prepared shell that they had laid on the beach. Inside the shell was a device that mimicked the vibrations produced by small or large crabs.

From their perspective, behind an umbrella located several meters away, scientists observed hermit crabs approaching the carapace, which provided a spacious, open-plan living space a few steps from the beach. When a new hopeful tenant touches the shell, they press a button that randomly determines whether the shell is vibrating strongly, weakly, or not at all.

"When they feel the strong vibration, they withdraw immediately. But when it is weak, they will be much more likely to try to overturn the shell, which is the first step in escalating the conflict, as this is the only way to get in the door, "said Laidre. "If there is no vibration, they hold it for a long time, but the wires prevent them from flipping the hull back."

While writing in Biology Letters, scientists explain that vibrations are a neglected aspect of animal communication. Next, they hope to investigate the unusual chirping noise produced by the hermit crabs when the expulsion is in progress.