Longevity has thrown the world into a tailspin lately as everyone tries to find the right tires to slap on their face as they wildly swim their way to eternal life – but can we learn the secrets of long life from nature? And if so, what does the world’s longest-lived vertebrate say about all this?
New experimental research on the subject has revealed that metabolic activity may be the key to the incredibly long lives of Greenland sharks. This increased understanding could help us conserve them on a warming planet, while also informing interventions for human cardiovascular health.
Greenland sharks – known to science as Somniosus microcephalus – have a lifespan of at least 270 years, but can live more than 500 in the most extreme cases (which, surprisingly, we know about thanks to nuclear weapons). It has long been suggested that the cold environment they inhabit, combined with the minimal effort they make to move, may be the key – but a team including Ewan Camplisson, a PhD student at the University of Manchester, UK, decided to take a closer look. .
In pursuit of the adaptations that allow Greenland sharks to live so long, the team performed enzyme analysis on preserved muscle tissue samples. Such samples are a rare opportunity to study these animals, which are the focus of the University of Copenhagen’s Old And Cold project.
Greenland shark tissue collection.
Image credit: Ewan Camplisson
“While on the expedition, the main focus is to catch sharks to tag them with electronic and physical tags so that we can release them and then either monitor where they swim (via the electronic tag) or record how much they grow if they are recaptured and we can identify them through their physical tag,” Camplisson explained to IFLScience.
Occasionally during this process a shark is injured and may not survive being released. To avoid the shark’s unnecessary suffering, we may decide not to release it back into the water, but instead ethically euthanize it. In this case we collect samples for future work so that the animal is not wasted in any way and can still be used for science. Any shark scraps are also donated to local fishermen or hunters, who feed the shark meat to their sled dogs so that none of the animals are wasted.
The team used samples of red muscle in storage to measure the sharks’ metabolic enzyme activity with a spectrophotometer, looking at a range of different shark ages and environmental temperatures. Surprisingly, they observed no significant changes in the metabolic activity of muscles in the sharks, indicating that their metabolism does not decline with age – as we see in other animals – and may be a crucial contributor to their extreme longevity. .
“For us, this is important as most animals showing traditional signs of aging would show decreases in some enzyme activities and compensatory increases in others as they age,” said Camplisson. “This is all part of the natural metabolism as aging causes it to fail and change over time. The fact that we don’t see this in the Greenland shark suggests that they don’t show this traditional sign of aging.”
The results showed changes in environmental temperatures, showing that metabolic enzymes were significantly more active where it was warmer. According to Camplisson, this suggests that muscle metabolism is not adapted to the polar environment as otherwise there would be less of a temperature-related change in activity.
The team’s work continues in the hope that a better understanding of Greenland sharks can inform how they might respond to the planet’s rapidly changing climate, while also revealing insights that could be applied to the study of human cardiovascular health as we age.
“I have other projects focused on studying aging in the Greenland shark,” Camplisson said. “Looking at changes in metabolism is just one of these projects. However, within this small project, I plan to look at some other tissues in the Greenland shark that may show different metabolic profiles, and also look at some other enzymes that will give even greater insight into metabolism in this extraordinary species.”
The study is being presented at the Society for Experimental Biology Annual Conference in Prague on July 2-5, 2024.
