{"id":10620,"date":"2026-01-23T11:06:52","date_gmt":"2026-01-23T11:06:52","guid":{"rendered":"https:\/\/natharatmouchrika.net\/home\/?p=10620"},"modified":"2026-01-23T11:06:52","modified_gmt":"2026-01-23T11:06:52","slug":"bird-retinas-work-without-oxygen-and-now-scientists-know-how","status":"publish","type":"post","link":"https:\/\/natharatmouchrika.net\/home\/?p=10620","title":{"rendered":"Bird retinas work without oxygen, and now scientists know how"},"content":{"rendered":"

\"\"<\/p>\n

The light-sensitive tissue of birds\u2019 eyes is not supplied with oxygen by blood vessels \u2013 instead, it powers itself with a flood of sugar, and this may have evolutionary benefits<\/p>\n

A crucial part of birds\u2019 eyes is unlike any tissue known in vertebrate animals. Their retina \u2013 the light-sensitive layer at the back of the eye \u2013 sidesteps the near-universal need for oxygen by vacuuming up heaps of energy-rich sugar instead.<\/p>\n

The discovery solves a 400-year-old mystery about the physiology of birds\u2019 eyes. It is also a neurobiological paradigm shift, says\u00a0Christian Damsgaard<\/a>\u00a0at Aarhus University in Denmark.<\/p>\n

\u201cWe have the first evidence that some neurons can work without any oxygen, and they\u2019re found in the birds that fly around in our gardens,\u201d he says.<\/p>\n

Retinas detect light and relay this information as nerve signals to the brain. The tissues require a lot of energy and are sustained by oxygen and nutrients coursing through a mesh of blood vessels. But bird retinas are extremely thick, and no vessels weave into the tissue. It was a mystery how their retinas received enough oxygen to keep the deep stacks of important nerve cells alive.<\/p>\n

Damsgaard and his colleagues studied zebra finches (Taeniopygia guttata<\/em>) in the lab to find an answer. The team put tiny oxygen sensors in the finches\u2019 eyes and found that the inner layers of the retina weren\u2019t getting oxygen at all.<\/p>\n

\u201cThey get oxygen from the back of the eye, but it cannot diffuse all the way through the retina,\u201d says Damsgaard.<\/p>\n

The team measured the activity of metabolic genes in different parts of the retina. This showed that the oxygen-free areas were heavily using glycolysis, a process that can break down sugars without oxygen. However, it is a much less efficient option.<\/p>\n

\u201cYou need 15 times more glucose to generate the same amount of energy,\u201d says Damsgaard. So, how was the retina getting that much sugar?<\/p>\n

Enter the pecten oculi, a rake-shaped collection of blood\u00a0vessels found in birds\u2019 eyes. The pecten was discovered centuries ago, and researchers had speculated that it piped in oxygen. But the team\u2019s readings ruled that out. Instead, they discovered the pecten was practically soaking the retina in glucose \u2013 four times more than what brain cells suck up \u2013\u00a0to fuel its ravenous glycolysis engine.<\/p>\n

Luke Tyrrell<\/a>\u00a0at the State University of New York at Plattsburgh is surprised that birds would evolve to rely on such an inefficient process for their vision. \u201cThe retina \u2013 especially a bird retina \u2013 is one of the most energy-needy tissues in all\u00a0of the animal kingdom,\u201d he says.<\/p>\n

The thick, blood vessel-free retinas may have adapted to enhance birds\u2019 visual acuity, making the pecten sugar pump worth the evolutionary hassle. The oxygen-free retina may have also set the stage for some birds to evolve high-altitude migration flights, with their vision unaffected by low oxygen levels.<\/p>\n

For\u00a0Pavel N\u011bmec<\/a>\u00a0at Charles University in Prague, Czech Republic, the findings are a \u201cclear case that reminds us that evolution brings very counterintuitive solutions\u201d to physical hurdles.<\/p>\n

Damsgaard and his team wonder if human cells could eventually be modified to be more tolerant of harmful oxygen-free\u00a0conditions, such as in the aftermath of a stroke.<\/p>\n

Link :\u00a0https:\/\/www.newscientist.com\/article\/2512692-bird-retinas-work-without-oxygen-and-now-scientists-know-how\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

The light-sensitive tissue of birds\u2019 eyes is not supplied with oxygen by blood vessels \u2013 instead, it powers itself with a flood of sugar, and this may have evolutionary benefits A crucial part of birds\u2019 eyes is unlike any tissue known in vertebrate animals. Their retina \u2013 the light-sensitive layer at the back of the …<\/p>\n","protected":false},"author":1,"featured_media":10621,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[50],"tags":[],"class_list":["post-10620","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-science"],"yoast_head":"\nBird retinas work without oxygen, and now scientists know how - \u0645\u0648\u0642\u0639 \u0646\u0638\u0631\u0627\u062a \u0645\u0634\u0631\u0642\u0629<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/natharatmouchrika.net\/home\/?p=10620\" \/>\n<meta property=\"og:locale\" content=\"ar_AR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Bird retinas work without oxygen, and now scientists know how\" \/>\n<meta property=\"og:description\" content=\"The light-sensitive tissue of birds\u2019 eyes is not supplied with oxygen by blood vessels \u2013 instead, it powers itself with a flood of sugar, and this may have evolutionary benefits A crucial part of birds\u2019 eyes is unlike any tissue known in vertebrate animals. 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