Hermit crabs shake in their shells to get off competitors who have designs on their homes, scientists have found.
Field tests conducted on a beach in Costa Rica showed Pacific hermit crabs are swiftly deterred from ousting and incumbent when they sense strong vibrations coming from inside.
Researchers at Dartmouth College in New Hampshire set out to investigate the role of vibrations after noticing that land-dwelling crabs performed in shunting motion when others climbed on their backs.
Competition for desirable shells is so intense among Pacific hermits that the animals have no qualms about clambering on those they pass to gauge if they can out the current owner. Most only move up the property ladder when another crab dies or is evicted.
t "When someone jumps on them, they duck inside their shell and perform this shunting movement to them."
that by shaking in their shells, the crabs signal that someone is home to and intends to stay put.
In a series of field tests, Laidre and Roberts watched as hermit crabs approached at particularly well-appointed shell they had placed on the beach . From their vantage point behind an umbrella several meters away, the scientists looked at as a hermit crabs approached the shell, which offered spacious open-plan living only. a short walk from the sea. When a hopeful new tenant touched the shell, they hit a button which randomly selected whether the shell vibrated strongly, weakly, or not.
But when it's weak, they're much more likely to try to flip the shell over, which is the first step in escalating the conflict, because Laidre said. “If there is no vibration, they keep it for a long time, but the wires are prevented from turning the shell over.”
Next, they will investigate the unusual chirping sound that hermit crabs make when eviction is under way.