Crabs are popular for making noise; they often make harsh sound by rubbing their claws. Apart from that, another sound comes from the internal body of a crab. Till now, the reason behind the inner sound remained unclear. This time, scientists have solved the mystery. When crabs feel risky, they make grumbling noise using teeth in the stomach. Initially, the teeth in the stomach assist crabs in breaking down food. But they use those teeth in this way also. This case uncovers the secret of Atlantic ghost crab, which makes growling noises. Researchers have used laser and x-rays to reveal the crabs’ body parts from where the sound comes. As per scientists the digestive system or the grinding mechanism is liable for the mysterious internal noise.
Because of making sound from the stomach, Ghost crabs’ claws remain free for an attacking move and waving around. Scientists say it is the first-ever proof which reveals an animal using internal sound to interact. Jennifer Taylor, a marine biologist from the San Diego’s University of California, has led the laboratory research. Taylor and team have studied 30 Atlantic ghost crabs to reveal the origin of the sound. During the trial, they have used laser Doppler vibrometry. It is a technology which estimates the number of vibrations by using reflected laser light. Researchers had bounced a laser off the different parts of a crab. Thus the technique has assisted the team in recognizing from where exactly the mysterious sound comes from the crab’s body.
In the end, the authors conclude that the powerful vibrations came from the gastric mill of the animal. You might not be aware, but a crab has a strange system in the stomach which assists them in food digestion. They have tiny teeth that together form so-called gastric mill. In the case of ghost crabs, the gastric mill consists of a teeth structure similar to a comb. Besides, it has a central tooth sandwiched between those teeth. Taylor said, ghost crabs have a unique structure on their claws for making sounds, and they use this second technique as a back-up. Even more, they use the method to make a sound when their claws are already busy doing another work. The team has published its entire findings in the journal Proceeding of the Royal Society B: Biological Sciences.