The Longest-Lived Vertebrate: Secrets of the Greenland Shark

The Greenland shark swims silently in the freezing waters of the Arctic. Biologists recently sequenced the massive genome of this ancient predator to understand how it lives for centuries. By examining its unique DNA, scientists are finally uncovering the specific genetic mechanics that allow this vertebrate to reach 400 years of age.

The 400-Year-Old Mystery of the Deep

For decades, the lifespan of the Greenland shark remained a mystery. Because sharks have skeletons made of cartilage rather than bone, scientists cannot count calcified growth rings to determine their age.

In 2016, marine biologist Julius Nielsen published a groundbreaking study in the journal Science that changed everything. His team used radiocarbon dating on the eye lens proteins of 28 Greenland sharks. The proteins in the center of the eye lens form before the shark is born and remain unchanged throughout its life.

The results were shocking. The oldest female in the group was estimated to be 392 years old, with a margin of error suggesting she could have been up to 512 years old. This officially made the Greenland shark the longest-lived vertebrate on Earth. A 400-year-old shark swimming in the ocean today would have been born during the early 1600s.

Sequencing a Massive Genome

To find out exactly how these animals live so long, a team of researchers from the Leibniz Institute on Aging and Ruhr University Bochum took on the massive task of mapping the shark’s DNA. Lead researchers Arne Sahm and Steve Hoffmann published their comprehensive findings regarding the genetic sequence in 2024.

They discovered that the Greenland shark genome is enormous. It contains approximately 6.5 billion base pairs. That makes it roughly twice the size of the human genome.

To decode a genome this large, the researchers relied on a combination of advanced genetic technologies. They combined PacBio long-read sequencing with Illumina short-read technology. Long-read technology helps scientists see the larger structural layout of the DNA, while short-read technology provides the fine details with high accuracy. This dual approach allowed the team to accurately piece together the 6.5 billion base pairs without getting lost in repeating genetic codes.

Jumping Genes and DNA Repair

The researchers wanted to know why the genome was so large. They found that more than 70 percent of the Greenland shark’s DNA consists of transposable elements. Biologists often refer to these as jumping genes.

Jumping genes are sequences of DNA that can copy themselves and move to different parts of the genome. In humans and most other animals, a high number of jumping genes is highly destructive. They disrupt normal genes, cause dangerous mutations, and accelerate the aging process. Yet, the Greenland shark thrives despite having billions of them.

The genetic sequencing revealed a highly specialized defense system. The researchers discovered that the Greenland shark has evolved an unusually high network of duplicated genes dedicated specifically to DNA repair. Whenever a jumping gene causes damage, this robust network of repair genes springs into action. They fix the broken DNA strands almost immediately. By constantly repairing genetic damage on a cellular level, the shark prevents the decay that causes aging and diseases like cancer. This extreme genetic stability is the core secret to their 400-year lifespan.

Cold Water and Slow Metabolism

Genetics only tell part of the story. The shark’s environment plays a massive role in its survival. Greenland sharks live in the deep, frigid waters of the North Atlantic and Arctic Oceans. The water temperatures there range from -1 to 10 degrees Celsius.

Living in such extreme cold forces the shark to have an incredibly slow metabolism. Everything about the animal operates in slow motion. Their heart beats only once every 10 to 12 seconds. They swim at a sluggish pace of about 0.76 miles per hour.

This slow metabolic rate drastically reduces the production of free radicals. Free radicals are unstable molecules that damage cells over time. By producing fewer free radicals, the shark experiences much less oxidative stress, which further protects its tissues from degrading.

Late Bloomers: Growth and Reproduction

Another fascinating aspect of their slow-motion life is their reproductive timeline. Because they age so slowly, Greenland sharks are the ultimate late bloomers. Marine biologists estimate that these sharks grow only about one centimeter per year.

Since a fully grown female can reach lengths of 16 to 24 feet, it takes a very long time for them to reach adulthood. Research indicates that a female Greenland shark does not reach sexual maturity until she is around 150 years old.

This delayed maturity is a direct result of their slow metabolism and cold environment. However, it also makes the species highly vulnerable to overfishing. If a shark takes 150 years to replace itself, any sudden drop in population numbers can be devastating to the ecosystem.

What This Means for Human Medicine

Biologists sequence these genomes because the longevity mechanics of the Greenland shark could eventually help human medicine. Cancer is fundamentally a disease caused by DNA damage and unchecked mutations.

If scientists can fully map the specific proteins and enzymes the shark uses to repair its DNA so efficiently, they might find new ways to treat human age-related diseases. Understanding how a 400-year-old shark prevents tumors despite having 6.5 billion base pairs of DNA could lead to highly effective new therapies in the future.

Frequently Asked Questions

How do scientists know the age of a Greenland shark? Scientists cannot use traditional methods like counting growth rings in bones because sharks have cartilaginous skeletons. Instead, researchers use radiocarbon dating on proteins found in the center of the shark’s eye lens. These proteins are formed before birth and remain unchanged, acting as a time capsule for the animal’s exact age.

Where do Greenland sharks live? Greenland sharks primarily inhabit the freezing depths of the North Atlantic and Arctic Oceans. They are typically found at depths ranging from 400 to 7,200 feet, where the water is near freezing and completely dark.

Are Greenland sharks dangerous to humans? There are no verified reports of a Greenland shark attacking a human. They live in extreme depths and freezing waters where human swimmers do not go. Furthermore, their incredibly slow swimming speed makes them highly unlikely to hunt fast-moving prey.

Why is the Greenland shark genome so large? The genome is massive, containing 6.5 billion base pairs, largely because over 70 percent of it consists of transposable elements. These are repeating DNA sequences that copy and insert themselves throughout the genome over millions of years of evolution.