Sharks Can Live for Hundreds of Years

Greenland sharks can live over 400 years, making them the longest living vertebrates known to science. The oldest Greenland shark ever found was estimated to be between 272 and 512 years old, with the most likely age around 390 years. This means some sharks alive today were born before the United States existed and have survived through centuries of human history swimming slowly through Arctic waters.

How Scientists Discovered Their Age

Scientists discovered the extreme age of Greenland sharks using radiocarbon dating on the proteins in their eye lenses. Unlike most body tissues that constantly regenerate, the center of a shark's eye lens forms before birth and never changes. By analyzing carbon isotopes in the lens center, researchers can determine when that tissue formed. The technique revealed that Greenland sharks grow incredibly slowly at about 1 centimeter per year. Using the size of captured sharks and their growth rate, scientists calculated ages exceeding 400 years. One female measuring 5 meters long was determined to be approximately 392 years old, though uncertainty in the method means she could have been as old as 512 years.

Why They Live So Long

Greenland sharks live in extremely cold water between minus 1 and 10 degrees Celsius. Cold temperatures dramatically slow their metabolism, reducing the speed of biological processes that cause aging. Their heart rate is incredibly slow, and they move through the water at only 0.3 meters per second, slower than a human walking pace. This extremely low energy lifestyle reduces cellular damage that accumulates with age. Additionally, the cold stable environment of the deep Arctic ocean provides consistent living conditions with few temperature fluctuations. The combination of cold water, slow metabolism, and stable habitat allows these sharks to live several times longer than warm water species.

Extremely Slow Growth and Reproduction

Greenland sharks grow at one of the slowest rates of any shark species at approximately 1 centimeter per year. A shark measuring 4 meters long took about 400 years to reach that size. This slow growth means Greenland sharks do not reach sexual maturity until they are about 150 years old. Female Greenland sharks must survive for over a century before they can reproduce for the first time. This extremely delayed reproduction makes the species vulnerable to overfishing because populations cannot quickly recover from losses. The sharks give birth to live young, with litter sizes estimated between 10 and several hundred pups, though little is known about their reproduction because it occurs in deep water.

Life in the Arctic Deep

Greenland sharks spend most of their lives in deep cold waters between 200 and 600 meters below the surface. They inhabit the Arctic Ocean and North Atlantic, ranging from Greenland and Iceland to Canada and even as far south as the Gulf of Mexico in deep water. These sharks tolerate the crushing pressure of the deep ocean and near freezing temperatures that would kill most marine animals. During winter, some Greenland sharks move into shallower water where divers occasionally encounter them. Despite their size, reaching up to 7 meters and weighing over 1,000 kilograms, they move slowly and pose little threat to humans.

Diet and Hunting

Greenland sharks eat fish, seals, and carrion despite being nearly blind. Almost all adult Greenland sharks have parasitic copepods attached to their eyes that damage their vision. Scientists believe the sharks rely on smell and detecting vibrations to find food in the dark deep ocean. Their stomach contents reveal they eat fish like cod and halibut, as well as seals. Whether they actively hunt seals or scavenge dead ones remains debated. Some scientists think the extremely slow moving sharks could not catch healthy seals and instead feed on sleeping seals or carcasses. Others suggest the sharks use ambush tactics in murky water where seals cannot see them approaching.

Threats and Conservation

Greenland sharks face threats from commercial fishing bycatch. They accidentally get caught in nets set for other species and die before being released. Their extremely slow growth and late maturity mean populations cannot quickly recover from fishing pressure. The International Union for Conservation of Nature lists Greenland sharks as near threatened. Historically, people hunted Greenland sharks for their liver oil, but commercial fishing ended decades ago. Today, the biggest threat comes from climate change warming Arctic waters and altering the cold stable environment these ancient sharks need. Protecting Greenland sharks requires international cooperation to reduce bycatch and preserve Arctic marine habitats.