{"id":156733,"date":"2026-05-27T18:05:46","date_gmt":"2026-05-27T23:05:46","guid":{"rendered":"https:\/\/uwm.edu\/news\/?p=156733"},"modified":"2026-05-27T13:15:21","modified_gmt":"2026-05-27T18:15:21","slug":"uwm-research-sheds-new-light-on-the-evolution-of-hagfish-eyes","status":"publish","type":"post","link":"https:\/\/uwm.edu\/news\/uwm-research-sheds-new-light-on-the-evolution-of-hagfish-eyes\/","title":{"rendered":"UWM research sheds new light on the evolution of hagfish eyes\u00a0"},"content":{"rendered":"<p><span data-contrast=\"auto\">New research led by a University of Wisconsin-Milwaukee geoscientist provides insight into how one of the most primitive living vertebrates\u00a0evolved\u00a0its uniquely simple visual system. The study,\u00a0published\u00a0in Biology Letters on May 27, examines fossilized hagfish eyes to reconstruct how their modern, reduced structure came to be.<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"auto\">The study\u2019s lead author, Victoria McCoy,\u00a0assistant\u00a0professor\u00a0in UWM\u2019s Department of Geoscience, collaborated with researchers from the Field Museum\u00a0of Natural History, the Lauer Foundation for Paleontology, Science and Education, the David and Sandra Douglass Collection and the University of Ottawa.<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"auto\">Hagfish, often described as the most primitive living vertebrates,\u00a0possess\u00a0extremely simple eyes and are\u00a0nearly blind. Scientists have long hypothesized that their eyes evolved from more complex vertebrate eyes through a gradual loss of structures,\u00a0likely as\u00a0hagfish adapted to the dark, deep-sea environments they inhabit today.<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"auto\">To test this idea, McCoy and her colleagues analyzed exceptionally well-preserved fossils of\u00a0three extinct hagfish species\u00a0from the approximately\u00a0308\u00a0million-year-old\u00a0Mazon Creek site in northeastern Illinois. Unlike modern deep-sea habitats, this ancient environment was near\u00a0shore and well\u00a0lit.<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"auto\">The fossil evidence revealed that these early hagfish had eyes more developed than those of modern hagfish, yet still less complex than typical vertebrate eyes,\u00a0representing\u00a0an intermediate stage in eye reduction.<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"auto\">\u201cThis study shows that the hagfish eye didn\u2019t become\u00a0simple all\u00a0at once,\u201d said\u00a0Arjan Mann, curator of early\u00a0tetrapods\u00a0at the Field Museum. \u201cInstead, it evolved through a gradual, stepwise loss of complexity over millions of years. Importantly, some of these changes appear to have happened before hagfish moved into the low-light environments where they live today.\u201d<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"auto\">These findings challenge the long-held assumption that deep-sea conditions alone drove the degeneration of hagfish vision, suggesting instead that aspects of this evolutionary process began earlier.<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"auto\">The research emphasized the importance of fossil evidence in understanding evolutionary transitions.<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"auto\">\u201cFossils like those from Mazon Creek give us a rare window into evolutionary history,\u201d said\u00a0McCoy.\u00a0\u201cThey allow us to see intermediate forms that bridge the gap between ancient organisms and their modern relatives, helping us understand how dramatic changes,\u00a0like the reduction of a complex eye,\u00a0actually unfold over time.\u201d<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"auto\">The study highlights the importance of combining paleontological data with evolutionary biology to better understand how major anatomical transformations occur.<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"auto\">The\u00a0study\u00a0will be available upon publication\u00a0via\u00a0<\/span><a href=\"https:\/\/doi.org\/10.1098\/rsbl.2026.0127\"><span data-contrast=\"none\">this link.<\/span><\/a><span data-contrast=\"auto\">\u00a0<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/p>\n<p><b><span data-contrast=\"auto\">About UWM<\/span><\/b><span data-ccp-props=\"{}\"><br \/>\n<\/span><span data-contrast=\"auto\">The University of Wisconsin-Milwaukee has an ambitious mission as both a top-tier research university and an access institution, striving to ensure that students have equitable opportunities to earn a college degree. UWM educates a diverse student body of more than 23,000 students from 83 countries. About 43% of its undergraduates are first-generation college students. Its unique and top-rated programs include Wisconsin\u2019s only accredited schools of architecture and public health, the only North American school dedicated solely to freshwater sciences and a film program ranked among the top 50 in the world. It has the largest and top-rated online education program in Wisconsin. UW-Milwaukee partners with leading companies to conduct joint research, promote entrepreneurship, provide student internships and serve as an economic engine for southeastern Wisconsin. The Princeton Review named UW-Milwaukee a 2026 \u201cBest Midwestern\u201d university based on overall academic excellence and student reviews.<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/p>\n<p><span data-ccp-props=\"{&quot;134233117&quot;:false,&quot;134233118&quot;:false,&quot;201341983&quot;:0,&quot;335551550&quot;:1,&quot;335551620&quot;:1,&quot;335559685&quot;:0,&quot;335559737&quot;:0,&quot;335559738&quot;:0,&quot;335559739&quot;:160,&quot;335559740&quot;:279}\">\u00a0<\/span><b><span data-contrast=\"auto\">About\u00a0the Field Museum\u00a0of Natural History<\/span><\/b><span data-ccp-props=\"{&quot;134233117&quot;:false,&quot;134233118&quot;:false,&quot;201341983&quot;:0,&quot;335551550&quot;:1,&quot;335551620&quot;:1,&quot;335559685&quot;:0,&quot;335559737&quot;:0,&quot;335559738&quot;:0,&quot;335559739&quot;:160,&quot;335559740&quot;:279}\"><br \/>\n<\/span><span data-contrast=\"auto\">The Field Museum connects people to the natural world and the human story. Located on Chicago\u2019s iconic Lake Michigan shore, the Field is home to\u00a0nearly 40\u00a0million artifacts and specimens including the Chicago\u00a0Archaeopteryx\u00a0and the iconic\u00a0SUE\u00a0the\u00a0T. rex. Much like the Earth itself, the Field Museum is always evolving. Every day, we work to uncover the history of life on Earth and find ways to safeguard its future, while sharing the beauty and diversity of our planet with visitors from every corner of the globe.<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/p>\n<p><span data-ccp-props=\"{}\">\u00a0<\/span><\/p>\n<p><span data-ccp-props=\"{}\">\u00a0<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>New research led by a University of Wisconsin-Milwaukee geoscientist provides insight into how one of the most primitive living vertebrates\u00a0evolved\u00a0its uniquely simple visual system. The study,\u00a0published\u00a0in Biology Letters on May 27, examines fossilized hagfish eyes to reconstruct how their modern, reduced structure came to be.\u00a0 The study\u2019s lead author, Victoria McCoy,\u00a0assistant\u00a0professor\u00a0in UWM\u2019s Department of Geoscience, [&hellip;]<\/p>\n","protected":false},"author":39392,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":"","uwm_wg_additional_authors":[]},"categories":[202],"tags":[],"section":[],"display_categories":[],"related-coverage":[],"uwmnews-feed":[],"class_list":["post-156733","post","type-post","status-publish","format-standard","hentry","category-news-releases"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v27.5 (Yoast SEO v27.5) - https:\/\/yoast.com\/product\/yoast-seo-premium-wordpress\/ -->\n<title>UWM research sheds new light on the evolution of hagfish 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