Greenland sharks can reside for greater than 400 years — that means a number of the ones swimming the North Atlantic right now had been alive when Isaac Newton was — and virtually all of them spend these centuries functionally blind, navigating the deep ocean with parasites completely connected to their eyes.

The Greenland shark has change into a fixture of well-liked science writing in the way in which of a small variety of charismatic creatures: the immortal jellyfish, the deep-sea tube worm, the bristlecone pine. The story arrives in roughly the identical form every time it’s instructed. The shark lives for hundreds of years. Some of the biggest people alive within the North Atlantic right now might have been born earlier than or throughout Isaac Newton’s lifetime. Across these centuries, a parasitic copepod attaches to the cornea and stays there. The well-liked conclusion is that the sharks reside terribly lengthy lives, and that they spend virtually all of these lives blind.

The first a part of that story is well-supported. The second half has simply been revised, and the way in which it has been revised is extra attention-grabbing than the model it replaces.

We need to take a look at what occurred to the blindness declare, after which at what tends to occur when well-liked science meets a creature that lives for much longer than we do.

The 2016 paper and what it truly stated

The longevity declare rests on a single main supply: a 2016 paper in Science by Julius Nielsen and colleagues, based mostly on the University of Copenhagen with a small group of collaborating establishments. The group utilized radiocarbon relationship to the attention lens nuclei of 28 feminine Greenland sharks starting from 81 to 502 centimetres in size. The lens nucleus is beneficial for this work as a result of it kinds throughout embryonic growth and doesn’t flip over the way in which most tissues do. The carbon-14 captured on the centre of the lens displays atmospheric carbon-14 on the time of delivery.

The outcome was an estimated lifespan of not less than 272 years, with the 2 largest sharks within the pattern dated at roughly 335 and 392 years. The 392-year determine carries a confidence interval of plus or minus 120 years, which the favored model of the story tends to flatten. The cheap studying is that the species can reside for a number of centuries, that some people at present within the inhabitants had been born within the 1600s or 1700s, and that the exact higher restrict stays genuinely unsure.

The blindness declare has a separate origin. It comes from a sequence of papers throughout the Nineties and 2000s describing an infection by Ommatokoita elongata, a copepod parasite that attaches to the corneal floor, anchors itself with an adhesive construction known as a bulla, and feeds on the tissue. The 1998 paper by Borucinska and colleagues, six contaminated shark eyes in Victor Bay within the Canadian Arctic, concluded that parasitism “could lead to severe vision impairment, possibly including blindness”. That qualifier “possibly” did many of the work, and it was the half that regularly fell away in abstract after abstract, till “the sharks are functionally blind” turned the usual line.

What the brand new paper truly reveals

In January 2026, Lily Fogg, Dorota Skowronska-Krawczyk and colleagues on the University of Basel and UC Irvine published in Nature Communications what’s, in our studying, one of many first complete checks of the query. They current genomic, transcriptomic, histological and purposeful proof that the Greenland shark retains an intact visible system well-adapted to dim situations. The retinal tissue within the specimens they examined confirmed no indicators of degeneration throughout the age vary. The molecular equipment for processing low mild was current and energetic. The authors recognized DNA restore pathways within the retina that they argue assist protect photoreceptor operate throughout centuries.

The place to begin for the work was, on Skowronska-Krawczyk’s account, a video clip. She watched footage of a Greenland shark shifting its eyeball to trace a lightweight supply. Her remark was a biologist’s one: evolution doesn’t have a tendency to take care of a posh sensory organ that confers no profit. If the attention works sufficient to trace mild, one thing is being seen.

The shark is just not blind. The parasite is actual, typically current, and clearly does some native injury to the cornea. The animal sees by it, or round it, or despite it, nicely sufficient that the visible system has been actively preserved for hundreds of years reasonably than allowed to decay.

This is a extra attention-grabbing discovering than the one it replaces.

What we are inclined to do with very lengthy lives

In our studying of the favored protection of this species over the previous decade, there’s a sample price naming.

When a creature lives for much longer than we do, we are inclined to fill the hole between its life and ours with a narrative. The story tends to be both elegiac or tragic. The shark drifts by Arctic darkness, blind, historical, witnessing nothing. The body is often a projection. It is what a human imagines a 400-year life would really feel like, utilized to an animal whose precise expertise we’ve no strategy to entry. The parasites on the cornea change into a type of pure metaphor for the price of lengthy life.

The revision issues as a result of it removes the metaphor and replaces it with one thing extra strange and extra demanding. The shark is just not a tragic determine carrying its blindness by the centuries. It is an organism whose biology actively preserves visible operate on a timescale we do not need a transparent manner to consider. The attention-grabbing query is now not what it have to be prefer to reside for 400 years blind. It is what it could take to protect a retina that lengthy. The Fogg paper factors at a part of the reply. Most of the reply is just not but identified.

A small be aware about obtained knowledge

The blindness line has been repeated in roughly the identical type for roughly thirty years. It turned a truth concerning the species with out anybody working the experiment that might affirm or refute it. The 1998 paper hedged fastidiously. The summaries didn’t. By the early 2020s the hedging had vanished fully from well-liked accounts.

There isn’t any scandal on this. It is how obtained knowledge tends to type about creatures most of us won’t ever see, in environments most researchers can not simply attain. Someone makes a cautious declare with a qualifier. The qualifier drops. The cautious declare hardens right into a identified factor. Eventually somebody watches a video, notices an animal shifting its eye, and goes again to look.

The shark remains to be there. It remains to be very previous, nonetheless very sluggish, nonetheless monitoring mild at a depth the place there may be not very a lot of it. The story we’ve been telling about it was a 3rd unsuitable, and the third that was unsuitable turned out to be the half we discovered best to think about.