2026-01-05 カリフォルニア大学アーバイン校(UCI)
Because the Greenland shark lives in the dim depths of the ocean and is often infested with parasites that attach to its eyes, scientists believed the large, long-lived species to be functionally blind. But UC Irvine researcher Dorota Skowronska-Krawczyk and colleagues have disproved this, challenging what is known about aging, vision and longevity. Courtesy of Ghislain Bardout
<関連情報>
- https://news.uci.edu/2026/01/05/eye-opening-research/
- https://www.nature.com/articles/s41467-025-67429-6
- https://www.science.org/doi/10.1126/science.aaf1703
最も長生きする脊椎動物であるニシオンデンザメの視覚系 The visual system of the longest-living vertebrate, the Greenland shark
Lily G. Fogg,Emily Tom,Maxime Policarpo,William Cho,Fangyuan Gao,Doreen Hii,Aaron E. Fawcett,Nicolas Boileau,Amalie Bech-Poulsen,Kirstine F. Steffensen,Cherlyn J. Ng,Peter G. Bushnell,John Fleng Steffensen,Richard Brill,Walter Salzburger & Dorota Skowronska-Krawczyk
Nature Communications Published:05 January 2026
DOI:https://doi.org/10.1038/s41467-025-67429-6
Abstract
The Greenland shark (Somniosus microcephalus) is the longest-living vertebrate and inhabits the exceptionally dim and cold waters of the Arctic deep sea. Due to its extreme lifespan, harsh environmental conditions, and prevalent corneal parasitisation, the Greenland shark has previously been thought to have impaired or degenerated vision. Here, we present genomic, transcriptomic, histological and functional evidence that the Greenland shark retains an intact visual system well-adapted for life in dim light. Histology and in vitro opsin expression revealed visual adaptations typical of deep-sea species, including densely packed, elongated rods and a short-wavelength shift in rod visual pigment sensitivity compared to shallow-water sharks. In situ hybridisation confirmed the presence of essential visual cell types: rods, Müller glia, and bipolar, amacrine, and ganglion cells. Moreover, despite being over a century old, the examined specimens showed no obvious signs of retinal degeneration. Using whole genome and retinal RNA-sequencing, we further show that dim-light (rod-based) vision genes are intact and robustly expressed, while many bright-light (cone-based) vision genes have become pseudogenized and/or are no longer expressed. Finally, we identify robust expression of DNA repair-associated genes in the retina, which may help support long-term maintenance of retinal integrity over the Greenland shark’s extreme lifespan.
眼水晶体の放射性炭素分析により、グリーンランドサメ(Somniosus microcephalus)の寿命が数世紀に及ぶことが明らかになった Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus)
Julius Nielsen、 Rasmus B. Hedeholm、 Jan Heinemeier、 Peter G. Bushnell、 […]、 John F. Steffensen
Science Published:12 Aug 2016
DOI:https://doi.org/10.1126/science.aaf1703
Deep living for centuries
We tend to think of vertebrates as living about as long as we do, give or take 50 to 100 years. Marine species are likely to be very long-lived, but determining their age is particularly difficult. Nielsen et al. used the pulse of carbon-14 produced by nuclear tests in the 1950s—specifically, its incorporation into the eye during development—to determine the age of Greenland sharks. This species is large yet slow-growing. The oldest of the animals that they sampled had lived for nearly 400 years, and they conclude that the species reaches maturity at about 150 years of age.
Science, this issue p. 702
Abstract
The Greenland shark (Somniosus microcephalus), an iconic species of the Arctic Seas, grows slowly and reaches >500 centimeters (cm) in total length, suggesting a life span well beyond those of other vertebrates. Radiocarbon dating of eye lens nuclei from 28 female Greenland sharks (81 to 502 cm in total length) revealed a life span of at least 272 years. Only the smallest sharks (220 cm or less) showed signs of the radiocarbon bomb pulse, a time marker of the early 1960s. The age ranges of prebomb sharks (reported as midpoint and extent of the 95.4% probability range) revealed the age at sexual maturity to be at least 156 ± 22 years, and the largest animal (502 cm) to be 392 ± 120 years old. Our results show that the Greenland shark is the longest-lived vertebrate known, and they raise concerns about species conservation.
