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Listen as a ghost crab deterred enemies – its stomach growls science

Jennifer Taylor

0, 2019, 7:01 PM

Apart from Disney's Sebastian and Tamatoa, crabs are not known for their acoustic abilities. The ghost cancer can change that. The crustaceans that live on the beach can produce noisy claws, not only with their claws, but also with their guts, as new research shows Atlantic coastal beaches of the United States could cause noise by rubbing a series of ridges on their claws, much like crickets do , This "stridulation" is often a reaction to threats – either from a predator or other ghost crab. It is believed that the sounds are both a warning (like the rattle of a rattlesnake) and an indicator of the size and strength of a crab. The scientists set up a series of microphones around ghost crab tanks and provoked the animals with sticks, other crabs or spidery remote-controlled toys. A vibration-sensitive laser in combination with X-ray imaging allowed the team to locate a claw-free sound resulting from a small, comb-like structure that the crabs use to grind food in their foregut (the so-called gastric mill). By rubbing the teeth of the comb over another structure called the middle tooth, the animals can produce a sound resembling claw-stridulation (see below). The frequency (about 2 kilohertz) is audible to many of the common enemies of crabs such as birds and raccoons, as well as to other ghost crabs (and humans).

Using the Stomach Mill to communicate frees the claws of the ghost crabs. Fighting and Defense even allow the animals to communicate during the fighting and allow them to spread their size to intimidate rivals. The researchers predict that the crabs may need their claws to make sounds when the threat is farther away. Then switch to the gastrointestinal system when the danger comes.

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