\n<\/p>\n
September 5, 2025<\/p>\n
2 min read<\/p>\n
This Gloriously Weird Fish Has Teeth on Its Forehead for Sex<\/p>\n
Researchers have finally traced the origin of the spotted ratfish\u2019s bizarre forehead teeth, which are used for mating<\/p>\n
By Kate Wong edited by Jeanna Bryner<\/span><\/p>\n The researchers identified teeth on the tenaculum of ancient relatives to the modern adult male spotted ratfish. This fossil record helped them establish the historical significance of this structure, brought to life by local artist Ray Troll.<\/p>\n The spotted ratfish is a two-foot-long fish with a big head and a long, skinny tail that lives in the northeastern Pacific Ocean. It belongs to a group of fish called chimaeras that are closely related to sharks. (Chimaeras are sometimes called ghost sharks.) Like most vertebrate creatures, it has teeth in its mouth. Unlike other vertebrates it also has teeth in another location: its forehead. It uses these forehead teeth for sex.<\/p>\n Researchers have long wondered where the ratfish\u2019s forehead teeth come from. New research, published on September 4 in the Proceedings of the National Academy of Sciences USA, has traced their origin.<\/p>\n The ratfish\u2019s extra teeth line a cartilaginous appendage called a tenaculum that in males can be erected and deployed to grasp a female during mating. Many fish have clasping appendages near the pelvis that they use to hold their mate close during the deed. The spotted ratfish has the tenaculum in addition to pelvic claspers.<\/p>\n If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. 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 Scientists have known about the ratfish\u2019s toothy tenaculum for a while. But they weren\u2019t sure exactly how the teeth originated or how they ended up in this weird location outside the mouth. Many of the ratfish\u2019s close relatives\u2014the sharks, rays and skates\u2014have toothlike structures in their skin called denticles that are made of the same material as teeth but are not true teeth. Are the ratfish\u2019s forehead teeth just modified skin denticles, or do they share their structure and origin with mouth teeth?<\/p>\n To find out, Karly Cohen of the University of Washington and her colleagues traced the development of the ratfish\u2019s tenaculum using micro-CT scans and tissue samples, and they compared the modern fish with fossil ancestors. The researchers determined that the ratfish\u2019s forehead teeth are true teeth\u2014they develop from a structure called the dental lamina that is present in the jaw but not in skin denticles. The dental lamina has never been found outside of the mouth until now.<\/p>\n \u201cThis insane, absolutely spectacular feature flips the long-standing assumption in evolutionary biology that teeth are strictly oral structures,\u201d Cohen said in a press release. Who knows where they\u2019ll turn up next?<\/p>\n If you enjoyed this article, I\u2019d like to ask for your support. Scientific American<\/span> 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<\/span> subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm <\/span>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<\/span>, 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, brilliant infographics, can’t-miss newsletters, must-watch videos, challenging games, and the science world’s best writing and reporting. You can even gift someone a subscription.<\/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":" September 5, 2025 2 min read This Gloriously Weird Fish Has Teeth on Its Forehead for Sex Researchers have finally traced the origin of the spotted ratfish\u2019s bizarre forehead teeth, which are used for mating By Kate Wong edited by Jeanna Bryner The researchers identified teeth on the tenaculum of ancient relatives to the modern<\/p>\n","protected":false},"author":1,"featured_media":19339,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[58],"tags":[11846,11847,6982,4113,2818,2174],"class_list":{"0":"post-19338","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-fish","9":"tag-forehead","10":"tag-gloriously","11":"tag-sex","12":"tag-teeth","13":"tag-weird"},"_links":{"self":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts\/19338","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=19338"}],"version-history":[{"count":0,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts\/19338\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/media\/19339"}],"wp:attachment":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=19338"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=19338"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=19338"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}On supporting science journalism<\/h2>\n
It\u2019s Time to Stand Up for Science<\/h2>\n