We all know how maddening an unreachable itch can be. Galapagos sharks have found a creative solution to this problem: manta rays, apparently, make excellent snout scratchers.At three different dive sites off Mexico\u2019s Revillagigedo archipelago between December 2024 and January 2026, scientists spotted Galapagos sharks rubbing their bodies against the top and bottom surfaces of manta rays.<\/p>\n
The mantas<\/a>\u2014gentle ocean giants who have no means of defense except their size\u2014seemed to tolerate this behavior from juvenile sharks, only shuffling mildly in response. With adult sharks, however, they went into flight mode, rolling backward and trying to escape a potential bite. But researchers are confident that the scraping behavior isn\u2019t hostile. The sharks specifically rubbed their snout and gill regions, known hotspots for sea lice, which suggests the mantas were being used as giant scratching posts.<\/p>\n On supporting science journalism<\/p>\n If you’re enjoying this article, consider supporting our award-winning journalism by subscribing<\/a>. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.<\/p>\n A total of eight such shark-manta encounters have been documented by two separate groups of researchers, who published their observations in Marine Biodiversity<\/a> and Environmental Biology of Fishes<\/a>.<\/p>\n \u201cThe sharks know that the surface of the manta is like sandpaper, so it\u2019s a good surface to remove those parasites,\u201d says Mauricio Hoyos, a co-author of the latter study and director of the marine conservation nonprofit Pelagios Kakunj\u00e1.Previously, Galapagos sharks were spotted scratching their snouts and gills on whale sharks. Shark skin, like that of manta rays, is made up of dermal denticles<\/a>, which are shaped like teeth, sharp and rough. \u201cThat\u2019s why they\u2019re nice places to scratch,\u201d explains marine ecologist Jane Vinesky, lead author of the same study and a Ph.D. student at Pelagios Kakunj\u00e1.<\/p>\n Typically, when sharks have a parasite problem, they pop into a cleaning station\u2014nature\u2019s own spa, where small \u201ccleaner fish\u201d peck parasites off their clients. But sometimes these cleaning stations get crowded. This competition might be driving some sharks toward alternative strategies, Hoyos says.Gregory Skomal, a marine biologist who heads the Massachusetts Shark Research Program and was not involved in either study, has seen smaller fish use sharks as exfoliators<\/a> to scrape off parasites. He finds the newly observed shark-manta interaction \u201cunique and exciting.\u201d<\/p>\n Scientists aren\u2019t sure how sharks learned to do this\u2014Hoyos wonders whether they\u2019d gotten the idea when smaller fish scratched their own itches on the sharks, while Skomal suspects individuals simply tried it one day, found out it worked and kept doing it. \u201cIn the world of sharks,\u201d Skomal says, \u201ca lot of what they do involves trial and error.\u201d<\/p>\n It\u2019s Time to Stand Up for Science<\/p>\n If you enjoyed this article, I\u2019d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.<\/p>\n I\u2019ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.<\/p>\n If you subscribe to Scientific American<\/a>, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.<\/p>\n In return, you get essential news, captivating podcasts<\/a>, brilliant infographics, can’t-miss newsletters<\/a>, must-watch videos, challenging games<\/a>, and the science world’s best writing and reporting. You can even gift someone a subscription<\/a>.<\/p>\n There has never been a more important time for us to stand up and show why science matters. I hope you\u2019ll support us in that mission.<\/p>\n","protected":false},"excerpt":{"rendered":"We all know how maddening an unreachable itch can be. 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