Ghost crabs 'growl' from their stomachs, scientists find


Ghost crabs us aren't ghosts but they are ghost like partly because of their Pale coloring and partly because like a vengeful spirit trapped in your walk in closet they they want you to get out. They can't whale like actual ghosts but but when scientists studied the way that goes crabs communicate when threatened they did hear something surprising. Professor Maya degrees was part of the team at the Scripps Institution of oceanography that discovered the ghost crabs secret Britt noisy weapon. We reached her in Sea Ranch California professor degrees. What did you uncover about. These unusual sounds that the ghost crabs make right so it was really interesting in the lab. We noticed that they were making the same sounds with another. They're part of their body than their claws and a lot of crustaceans. Make these really neat. Strangulation sounds or grinding sounds that are really important for their behavior h-have yer but we heard it coming from another part of the body which was very intriguing before we find out what part of the body's doing let's hear a bit of the sound that you have recorded a growling crabs okay. That's the sound Dallas would that is great so it sounds like a scraping sound as you could tell when a two body parts scraped together and what we found is that it was actually coming from the stomach so what the animals have is a gastric mill which is basically thickly what they use to grind food in their stomachs. It's a set of teeth basically in the stomach and they can chew up food that way but we learned that they can also also make these sounds that sounds strikingly similar to the sounds that they make with their claws. Do all crabs have these grinding mills in their guts. Yes all crustaceans nations that we know of these gastric males or yeah grinding apparatus says it's pretty crazy but did you know of any that actually used the grinding mill to nor to make a sound. That's nothing to do with digesting food. nope this is the first example of really any animal making sounds communication with their stomachs. As far as we know when he first identified this sounds you could see that they weren't doing it with their claws. What did you think was going on yeah. It was really neat. The lead author of the Study Jennifer Taylor had actually brought out these animals into the lab for another study she was going to look at how they behave antagonistically to each other but then she noticed that they were making in kind of classic sound not with their claws and she got very curious and kind of brought the rest of the team to kind of figure out where the sound is coming from what what did you do in order to figure it out. I we used a laser doppler vibe Rahmatullah which is basically vibration sensing lasers to able to pinpoint where in the body the sounds coming from so that told us that the sound was coming from the body cavity probably this gastric mill but we need his see the gastric mill actually moving at the same time that the sound was being produced and that's actually really tricky to jail in bigger crowds. You can stick like an endoscope down L. Nancy the gastric mill moving but these are really small crabs kind of the size of your hand and when they make the sound they're moving around a lot so it's pretty hard to do so we actually teamed up with a group of medical doctors at Uc San Diego Medical Center and we use their radiology technology so basically weekly x Ray imaging to be able to make movies of the animals making the sound while they were moving their gastric. Mill says anyone x ray to grab before as far as you know you know not in this way certainly not with late human technology and medical technology so this is definitely the first time that they had stopped crafts into this machine before but it worked and it was really exciting they make this sound in order to when they're threatened when they're trying to ward off attacks or they're trying to antagonize agonize another another species so what what did you do in order to get them to make the sound they actually do it when they're in tag amazing other individuals from the same they're same species usually and so we actually able to use bodies of dead crabs of the same species and we actually even also so put live crabs in with them but really be able to monitor where they were going and kind of guide the animals were going to be doing these behaviors. Here's we used robotic expert toys and their remote controlled toys and so we were able to remotely control the antagonizing toy to be able to get the crabs to make the

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