{"id":213468,"date":"2025-09-09T18:21:08","date_gmt":"2025-09-09T18:21:08","guid":{"rendered":"https:\/\/www.europesays.com\/us\/213468\/"},"modified":"2025-09-09T18:21:08","modified_gmt":"2025-09-09T18:21:08","slug":"this-bizarre-fish-has-8-rows-of-forehead-teeth-it-uses-during-sex","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/us\/213468\/","title":{"rendered":"This Bizarre Fish Has 8 Rows of Forehead Teeth It Uses During Sex"},"content":{"rendered":"

Spotted ratfish<\/a> are scaleless, rabbit-faced deep-sea fish, about two feet (61 centimeters) long, and native to the northeastern Pacific Ocean. As if that wasn\u2019t a strange enough description, these distant shark cousins also feature teeth on their foreheads.<\/p>\n

While a number of marine animals, such as sharks, rays, and whale sharks<\/a>, have external tooth-like structures called denticles, it turns out the spotted ratfish\u2019s toothy features are straight-up true teeth, as true as the ones in your mouth. And they use them for sex.<\/p>\n

Researchers have revealed that the structures on the male spotted ratfish\u2019s tenaculum\u2014an appendage on its forehead\u2014are real teeth. This discovery could have significant implications for the evolutionary history of teeth. Plus, researchers now get to wonder, in what other funky places could teeth be growing?<\/p>\n

\u201cMale chimaeras develop an articulated cartilaginous facial appendage, the tenaculum, which is covered in an arcade of tooth-like structures,\u201d the researchers wrote in a study<\/a> published last week in the journal PNAS. \u201cThese extraoral teeth remain poorly understood, and their evolutionary origin is unclear. We investigate the development of the tenaculum and its teeth throughout the ontogeny of the Spotted Ratfish, Hydrolagus colliei.\u201d<\/p>\n

Underwater sex is hard <\/p>\n

Spotted ratfish erect their tenaculum to scare off competition and hold onto females\u2019 pectoral fins while mating. After all, it must be hard to make love underwater with no arms. So much so that these deep-ocean fish are endowed with a second tool\u2014denticle-covered pelvic claspers\u2014to make sure their mate doesn\u2019t float away. When the tenaculum is erect, it\u2019s hooked and barbed with up to seven or eight rows of retractable and flexible teeth. When it\u2019s not in use, however, it\u2019s small and white.<\/p>\n

\u201cThis insane, absolutely spectacular feature flips the long-standing assumption in evolutionary biology that teeth are strictly oral structures,\u201d Karly Cohen, a biologist<\/a> at the University of Washington, said in a university statement<\/a>. \u201cThe tenaculum is a developmental relic, not a bizarre one-off, and the first clear example of a toothed structure outside the jaw.\u201d<\/p>\n

To investigate whether the tenaculum\u2019s structures were denticles or real teeth, the researchers studied the tenaculum of hundreds of fish. They also compared the fish to their ancestral fossils. These approaches revealed that both male and female ratfish develop the start of a tenaculum, but only in males does it grow into a little white pimple (ew, not my description) that extends on the forehead. The structure attaches to jaw muscles, breaks through the surface of the skin, and grows teeth. Thank goodness my pimples have never done that.<\/p>\n

The tenaculum\u2019s teeth are rooted in the dental lamina\u2014jaw tissue that, until now, researchers hadn\u2019t seen anywhere else. \u201cWhen we saw the dental lamina for the first time, our eyes popped,\u201d Cohen explained. \u201cIt was so exciting to see this crucial structure outside the jaw.\u201d<\/p>\n

Real teeth <\/p>\n

Part of the excitement was surely due to the fact that skin denticles don\u2019t have a dental lamina, suggesting that the tenaculum\u2019s teeth are exactly that: teeth. The researchers further bolstered this theory with genetic evidence, revealing that genes linked to vertebrate teeth were expressed in the tenaculum. These genes were not expressed in the denticles. Furthermore, the team identified hints of teeth on related species\u2019 tenaculum in the fossil record.<\/p>\n

\u201cWe have a combination of experimental data with paleontological evidence to show how these fishes coopted a preexisting program for manufacturing teeth to make a new device that is essential for reproduction,\u201d said Michael Coates, a co-author of the paper and the University of Chicago\u2019s chair of organismal biology and anatomy.<\/p>\n

\u201cChimeras offer a rare glimpse into the past,\u201d Cohen concluded. Chimaeras are a group of cartilaginous fish, including spotted ratfish. \u201cI think the more we look at spiky structures on vertebrates, the more teeth we are going to find outside the jaw.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"Spotted ratfish are scaleless, rabbit-faced deep-sea fish, about two feet (61 centimeters) long, and native to the northeastern…\n","protected":false},"author":3,"featured_media":213469,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[16278,9251,159,90885,67,132,68],"class_list":{"0":"post-213468","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-evolution","9":"tag-fish","10":"tag-science","11":"tag-teeth","12":"tag-united-states","13":"tag-unitedstates","14":"tag-us"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@us\/115175730993503629","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/213468","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/comments?post=213468"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/213468\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media\/213469"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media?parent=213468"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/categories?post=213468"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/tags?post=213468"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}