Determining the world’s oldest living animal involves drawing a distinction between the longest-lived individual and the species with the greatest potential lifespan. Scientists must define what constitutes an “individual” animal, which excludes colonial organisms like corals and sponges that may technically live for thousands of years as a collective. The record holder for extreme longevity often changes as new measurement technologies allow researchers to accurately verify ages. The challenge lies in obtaining a verified age for a wild animal, a process that frequently requires the animal’s death to examine internal tissues for an accurate count.
Identifying the World’s Oldest Living Animal
The single oldest verified individual animal was an ocean quahog clam, Arctica islandica, found off the coast of Iceland in 2006. This deep-sea clam, nicknamed “Ming,” was calculated to be 507 years old at the time of its discovery. Its remarkable lifespan meant it was alive when the Ming Dynasty ruled China, which is how it earned its moniker. The age was determined by counting the annual growth rings within the clam’s shell, a method similar to dendrochronology for trees. Ocean quahogs thrive in the cold, stable environment of the North Atlantic seabed, which contributes to their slow growth and exceptional longevity.
Other Extreme Longevity Champions
While the ocean quahog holds the non-colonial record, other animals demonstrate astonishing lifespans, especially in cold marine environments. The Greenland shark, Somniosus microcephalus, is the longest-lived vertebrate known, with a minimum life expectancy of 272 years. Individuals have been estimated to be nearly 400 years old, potentially reaching 512 years. These slow-moving, deep-dwelling predators do not even reach sexual maturity until around 150 years of age.
The bowhead whale, Balaena mysticetus, holds the record for the longest-living mammal, with some individuals estimated to live for over 200 years. This estimate was confirmed by the discovery of antique harpoon points lodged in the blubber of harvested whales. One male bowhead was estimated to be 211 years old using a technique that analyzes amino acids in its eye lens.
On land, giant tortoises are the champions of longevity. Jonathan, a celebrated Seychelles giant tortoise on the island of St. Helena, is believed to have been born around 1832, making him over 190 years old and still alive. While other tortoises may have lived longer, their ages are less reliably verified.
A different kind of longevity is found in the “immortal jellyfish,” Turritopsis dohrnii, which achieves biological immortality. When faced with environmental stress or injury, the adult medusa can revert its cells back to the juvenile polyp stage through a process called transdifferentiation. This restart of the life cycle means the jellyfish does not die of old age.
The Science of Aging Resistance
The exceptional longevity observed in these animals is linked to a combination of genetic and environmental adaptations. A consistently cold habitat, such as the deep ocean or Arctic waters, plays a significant role by slowing down metabolic processes. A slower metabolism reduces the rate of oxidative damage to cells and tissues, effectively slowing the aging process.
At a cellular level, many long-lived species possess highly efficient mechanisms for DNA repair and protein maintenance. Bowhead whales, for instance, have mutations in genes involved in DNA repair, which may provide enhanced protection against cancer. The ability to maintain cellular integrity and robustly repair molecular damage is a common biological signature across species with extreme lifespans.
Some long-lived organisms also seem to avoid or bypass the process of senescence, or biological aging. The regenerative capacity of the immortal jellyfish is an extreme example, as it completely reverses cellular differentiation to rejuvenate itself. Even in species that do age, like the ocean quahog, their very slow rate of growth and development suggests a prolonged period of physiological stability.
How Scientists Measure Extreme Age
Determining the age of animals that outlive human observers requires specialized and often invasive scientific techniques.
For marine invertebrates like the ocean quahog clam, scientists use sclerochronology, a method akin to tree-ring dating, counting the distinct annual growth layers deposited in the shell. This technique provides a precise chronological record of the animal’s life.
For vertebrates, a common method involves analyzing the eye lens, which contains proteins formed before birth that remain metabolically inert. In Greenland sharks, scientists apply radiocarbon dating to these proteins, using the radioactive carbon signature from mid-20th-century nuclear tests as a time marker. Another technique, aspartic acid racemization, measures the chemical change in amino acids within the eye lens to calculate age, used successfully for bowhead whales.
In fish, age is frequently determined by counting growth rings in otoliths, or ear stones. For giant tortoises, the most reliable age determination comes from historical records of their hatching or arrival in captivity. Newer, less invasive methods, such as epigenetic clocks that measure age-related changes in DNA methylation, are also being developed for many wild animal species.