The Long-Lived Greenland Shark

The Greenland shark, a mysterious inhabitant of the cold, deep waters of the North Atlantic and Arctic Oceans, possesses an extraordinary secret: it is the longest-living vertebrate on Earth. For a long time, scientists suspected these large, slow-moving creatures lived for many decades due to their size and sluggish growth, but accurately determining their age proved challenging because, unlike many other sharks, they lack hard tissues like fin spines or calcified vertebrae that typically show growth bands.

A breakthrough came with the use of radiocarbon dating on the sharks' eye lenses. The center of the eye lens contains proteins that form before birth and do not undergo metabolic turnover, essentially preserving a record of the shark's birth year. By analyzing these proteins, scientists were able to determine the age of Greenland sharks, revealing individuals that were several centuries old, with the oldest estimated to be nearly 400 years old, and potentially over 500 years. This remarkable longevity means some of these sharks were alive during historical events like the establishment of colonial settlements or the construction of famous landmarks.

The secret to their astonishing lifespan is deeply intertwined with their frigid, deep-sea environment. Living in near-freezing temperatures, the Greenland shark has an incredibly slow metabolism, which conserves energy and reduces the rate of cellular damage over time. This slow pace of life extends to their growth, at about one centimeter per year, and their reproduction; females do not reach sexual maturity until they are around 150 years old. Despite their sluggish movement, these apex predators are efficient hunters, preying on fish and seals, and even scavenging larger carcasses, adapting to their environment in truly unique ways.