The Greenland shark is the longest-living vertebrate in the world. Scientists estimate that the sharks can live for at least 250 years but can possibly reach up to 500 years.
It has never been understood why the creatures can live for so long, but now, researchers may have discovered the cause of their longevity—their metabolism.
Greenland sharks (Somniosus microcephalus) live in the Arctic and North Atlantic Ocean at depths of 8,684 feet.
Previously, it was assumed that their long lifespans were due to their cold environments. These sharks can survive in waters with temperatures as low as 29 degrees Fahrenheit.
However, new research has revealed that the sharks’ longevity may be because of their metabolic activity.
Unlike the metabolic activity in other animals, the sharks’ do not seem to change over time. The research was presented at the Society of Experimental Biology Conference, which was held in Prague from July 2 to July 5.
“This is important for us as it shows the sharks don’t show traditional signs of aging,” said Ewan Camplisson, the lead author of the study and a doctoral student at the University of Manchester.
In the new study, the researchers measured the sharks’ metabolism. Metabolism is the process of chemical reactions in the body’s cells that break down nutrients from food and drink and convert them into energy.
The energy is used for thinking, moving, growing, and building/repairing tissues. Metabolism also helps the body rid itself of toxic substances.
Olga Zarytska – stock.adobe.com – illustrative purposes only
The rate of metabolism slows down over time in most animals. This leads to decreased production of energy, slower repair of cells, and a reduced ability to remove cellular waste.
The researchers took muscle tissue samples from 23 Greenland sharks that were caught on the south coast of Disko Island in central Greenland.
Then, they examined the activity of five different enzymes in the samples to calculate their metabolic rate and determine their responses to various environmental temperatures.
By measuring the body length of each of the sharks, the researchers were able to guess their ages. They used a model from a 2016 study to estimate the age of Greenland sharks.
They found that the sharks ranged in age from 60 to 200 years. When they compared the sharks’ enzyme activity, they did not observe any changes across the different ages.
The Greenland sharks’ metabolism remained stable even as they got older, suggesting that they don’t degenerate like other animals do.
This is most likely the reason for their long lives. A series of tests showed that the enzymes had higher activity when subjected to warmer temperatures.
“The higher activity in warmer conditions would suggest that if these sharks were forced into a warmer environment, then their metabolism would increase significantly, which would likely alter their lifestyle,” Camplisson said.
It is expected that the temperatures of global sea surfaces will increase by 2.1 to 5.8 degrees Fahrenheit by 2100 because of global warming.
The researchers hope that further research can be conducted on the sharks’ metabolism to figure out ways to protect them as their environment undergoes rapid changes.
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