The Greenland shark needs only about 200 grams of fish each day to survive, with a lifespan that can reach several hundred years.
Slow Metabolism Throughout Life
By studying the metabolic rate, a research team led by Eric Ste-Marie at the University of Windsor, Canada, gathered valuable insights about the Greenland shark under environmental pressures. In a study published in the journal Experimental Biology, Eric Ste-Marie and colleagues examined the amount of food that the Greenland shark requires to survive each day.
Primarily distributed in the waters of the Antarctic and the North Atlantic, as well as around Greenland, the Greenland shark is a slow-moving species, with a body length ranging from 2.4 to 7 meters and weighing up to 1.5 tons.
This predatory fish specializes in eating salmon, eels, seals, and even polar bears if the opportunity arises. However, their meals are spaced far apart.
The Greenland shark has a very slow metabolism. (Photo: Dive Magazine).
It is one of the longest-living animals on Earth and the longest-living vertebrate in the world. Researchers believe that they can live up to 500 years. A study published in Science in 2016 estimated the age of 28 Greenland sharks, with the oldest individuals ranging from approximately 335 to 392 years old.
Eric Ste-Marie’s team captured 30 Greenland sharks over five years, tagging them, taking samples, and fitting them with biological sensors to collect information on their movement, body temperature, and water temperature. The results showed that Greenland sharks are very sluggish, moving around at a very slow pace. Using this information, the researchers were able to determine the caloric needs of the Greenland shark. Accordingly, an individual weighing about 227 kg needs to eat between 57 and 184 grams of fish or marine mammals to survive.
Recent research by PhD candidate Ewan Camplisson from the University of Manchester, UK, indicates that the metabolic rate of these sharks does not slow down with age. This may explain why sharks tend to live for such long periods. This process is different from that observed in most animals, including humans. For example, human metabolism tends to slow down as people age, which is why older adults are more likely to gain unhealthy weight.
By monitoring the activity of five metabolic enzymes in the muscle tissue of Greenland sharks, researchers found that in most species, the activity of these enzymes changes at different stages of the organism’s development.
Some enzymes decrease in activity over time as they may become aged or damaged, while others may later recover and increase in activity again to ensure that the body continues to produce enough energy.
In the studied Greenland sharks aged between approximately 60 and 200 years, there were no significant changes in enzyme activity. Of course, a 200-year-old Greenland shark may still be considered middle-aged, so this may not hold true when they enter their third or fourth century of life.
Moving forward, researchers will continue to investigate the activity of other enzymes to see if and how these enzymes change as the sharks age.
A photo of a Greenland shark, taken in Admiralty Inlet, Nunavut, Canada (Photo: /Wikimedia commons).
The Complex Process of Aging
These research findings will require a long process before they can be applied to improve human health, as aging is an extremely complex system that we do not fully understand.
For example, changes in metabolism are just one part of the aging process in humans. Genetic defects, protein instability, and other processes known as “signs of aging” are also involved. Researchers want to further explore these distinctive characteristics to determine whether Greenland sharks exhibit typical aging signs.
Although the unique aging characteristics of the Greenland shark have allowed them to live for centuries, this could also be a double-edged sword when faced with rapidly changing environments.
This species is classified as “vulnerable” by the World Conservation Union and may be too slow to adapt to climate changes, ocean pollution, and other harmful factors.
