Aging gracefully comes naturally to these creatures, which can live for hundreds, and sometimes even thousands, of years

Brian Handwerk

Science Correspondent

Life is short, the old saying goes, but in the world of animals, we humans are pretty fortunate: Our species is quite long-lived. With 122 being the oldest documented age, humans can enjoy decades more life than most fish, birds and mammals—including our primate relatives.

But we’re not alone in experiencing longevity. Other rare species reach ages marked in centuries, and each class of animals boasts individuals that are unusually long-lived compared to their peers. Aging wild animals isn’t always easy—they don’t have birth certificates. But we’ve searched the scientific record to identify some of the world’s oldest species and revealed their secrets to staying alive.

Giant tortoises are the longest-living reptiles

The world’s oldest living land animal, Jonathan the Seychelles giant tortoise, celebrates his unofficial 192nd birthday this December 4. His estimated birth year is 1832, the year Andrew Jackson won re-election. He was fully mature, thus at least 50, when he was gifted to the governor of Saint Helena island in 1882. But nobody knows his real age, and some experts suspect Jonathan was probably born even earlier. And this ancient individual isn’t an outlier among his kind. Seychelles giant tortoises average a 150-year life span, and related species can be similarly long-lived. How?

Genetic studies of Galápagos giant tortoises revealed variants that aid cancer suppression, anti-inflammatory immune responses and DNA repair. When some tortoise cells are subjected to age-related stresses, they tend to self-destructbefore they are damaged in ways that could produce cancer or other fatal illnesses. Other research suggests that part of the tortoise’s secret lies in its shell. A study of 77 species of reptiles and amphibians showed that species with protective shells aged five times more slowly than those without the coverings. One theory holds that since shells frequently prevent tortoises from being eaten by predators, shelled species tend to live longer, and over time that may have helped to produce evolutionary pressures to age more slowly.

Olms, the cave-dwelling salamanders, are the longest-living amphibians

In the lightless caves of Croatia and Slovenia, the olm cave salamander has adapted superpowers to thrive in an isolated environment across generations over some 20 million years. Olms enjoy extreme senses of smell and hearing, and the ability to hunt by detecting faint electrical fields of other animals in the water nearby. They have also become very long-lived among amphibians, averaging 69 years and reaching ages of 100 or perhaps more. Those estimates come from research out of a cave laboratory in Moulis, France, where scientist have tracked olm births and deaths for some 70 years.

Adult olms retain characteristics of their larval youth, like external gills, and show few signs of aging even as the decades pile up. But the reasons why they live so long aren’t clear. These salamanders go through life slowly with a low metabolism. They can go for years without eating and even spend years without moving much from a single location. But their metabolisms aren’t significantly lower than those of relatives that don’t live nearly as long. The olm’s caves are largely free from predators and external threats, so it’s possible that the environment encourages very high survival rates that in turn have somehow enabled olms to evolve extreme life spans.

Greenland sharks are the longest-living fish

Could a contemporary of William Shakespeare still be swimming in the sea? Greenland sharks inhabit the deep, dark, frigid waters of the Arctic and North Atlantic oceans—and they do so for an astoundingly long time. Radiocarbon dating techniques on the fish’s eye lenses have found living sharks that are around 400 years old, according to a 2016 study, which means they could have been alive during the Bard’s days.

In the frigid depths, the cold-blooded animals’ movements and metabolism slow dramatically. Greenland sharks’ metabolic rate is “just above a rock,” Chris Lowe, a shark biologist at the California State University at Long Beach, told Smithsonian magazine in 2016. Greenland sharks are slow-growing, less than half an inch per year, but live so long that mature specimens reach more than 19 feet in length. These sharks may not reach reproductive age until they are 150 years old—longer than any human has ever survived. Based on their growth rates and the size of some sharks, their maximum age could be as much as 500 years.

In September 2024, an international team sequenced the shark’s very large genome—a genetic code of 6.5 billion base pairs, twice as long as the human genome. Greenland sharks boast high numbers of repetitive or duplicate genes. That’s often considered detrimental to a genome, but in this case it may be beneficial for longevity because many of the duplicated genes help to repair DNA damage in cells.

Termite queens are the longest-living insects

Life is fleeting for most insects. “Generally insect life spans are measured in weeks to months,” says Floyd Shockley, an entomologist at the Smithsonian’s National Museum of Natural History. These species tend to reproduce at a tender age, having many young as quickly as possible, because their days are numbered.

But some social insects, like termites, employ a different strategy, and it enables their queens to defy death for 50 years or more. Among these insects, most individuals—the workers—are largely sterile and live just a few months. They spend that time supporting the queen’s efforts as an egg-laying machine—in some cases she’ll produce thousands a day for many years on end. “The queens reproduce nonstop upon reaching adulthood, and the reproductive cycle has many aspects to it that result in enhanced cellular regeneration,” Shockley explains. This genetic ability to regenerate cells keeps some queens going for decades, arresting their aging until they literally give out and run out of eggs. “At that point,” Shockley says, “they rapidly decline and die.”

Laysan albatrosses are the longest-living wild birds

Birds are relatively long-lived in the animal kingdom, averaging two to three times the life span of mammals of the same size, studies show. This longevity might be related to birds’ ability to fly. As evolution fine-tuned bird biology to engineer flight, building systems like strong muscles and efficient ways to process oxygen, it may have helped them to stay healthier longer—as well as enable them to fly away from potentially lethal situations.

Most adult birds don’t show many obvious physical signs of aging, which makes it difficult to know just how long they have been alive in the wild. But one unusual example, a Laysan albatross named Wisdom, is at least 74 years old and has just laid another egg. The oldest-known wild bird in the world, Wisdom was banded in 1956. During her annual wanderings she returns to Midway Atoll each year, usually in December. Scientists estimate that Wisdom has flown over three million miles in her long life, and fledged as many as 30 chicks.

Sponges are the longest-living invertebrates

Sponges aren’t the most dynamic animals; rooted to a spot on the seafloor, these filter feeders may appear more similar to plants than animals. But they have at least one jaw-dropping ability—survival. Glass sponge reefs found off British Columbia’s north coast are among the oldest in the entire ocean and have survived for more than 9,000 years.

In the East China Sea, scientists discovered the skeleton of a glass sponge that had lived for some 11,000 years. The sponge is so ancient that its remains constitute an archive of ancient climate in the sea. Under chemical analysis, scientists were able to reconstruct past environmental changes like ocean temperature shifts and the eruptions of underwater seamounts, which left their marks on the ancient sponge.

Fossils show that these sponges aren’t just long-lived individuals. As a group they are some of the earliest animals to appear on Earth. They may have been around as long as 890 million years ago—more than 600 million years before the dinosaurs emerged.

Elephants are some of the longest-living land mammals

Elephant memories are long, and so are their lives. African elephants can live up to 70 years, while their slightly smaller Asian elephant relatives may reach 60 years of age.

Big mammals like whales and elephants, which are less likely to die from predators or other accidents, tend to live longer lives. This in turn can spur evolutionary genetic and metabolic investments that protect against, or repair, the damage life exerts on cells. Elephants copy tumor-suppressing genes, for example, so that one can function if the other is damaged. That kind of anti-cancer adaptation is unlikely to arise in a short-lived small mammal, like a field mouse, that’s soon to become something’s dinner.

And while many species strive to reproduce before they die but don’t have a huge role once their reproductive days have passed, elephants are different. These giants have a social structure that values elders for many years after their peak reproductive period is over. Studies show that elderly female elephants are leaders, valued for their roles as caregivers for the young and for their experience and knowledge to evaluate predatory threats and make good decisions for the group.

Immortal jellyfish are the longest-living invertebrates

These tiny jellyfish have been drifting around the oceans since before the days of the dinosaurs—but how long has a single jellyfish lived? It appears to be biologically possible that, if not swallowed up by predators or killed by other factors, an immortal jellyfish could live indefinitely.

Like other jellyfish, the species’ fertilized eggs develop into a larva form, which then drops to the seafloor and grows into a colony of polyps. The polyps later morph into the recognizable, free-floating jellyfish forms known as medusas.

But incredibly, when faced with threats from injury to starvation, the immortal jellyfish can reverse the process, turning the clock backward. First the gelatinous layer thins out and the jellyfish settles on the bottom, where it becomes a cyst-like mass of cells. All features of the familiar “medusa” shape disappear. But within a few days it starts to show polyp features, and it begins the life cycle anew.

“The process is a true metamorphosis, albeit in opposite direction to the normal developmental cycle,” says Maria Pia Miglietta, who studies the evolution and ecology of the immortal jellyfish at Texas A&M University. Miglietta adds that the transformation from jellyfish to polyp may involve transdifferentiation—a process in which mature cells transform from one type to another entirely different type of cell.

Miglietta says that while the jellyfish life cycle has been reversed many times in the lab, nobody knows how often it happens or how long the jellyfish might survive in the wild. “Studying these animals in the ocean is hard,” she says, “and we haven’t figured out how to follow a two-millimeter jellyfish and see what happens to it.”

Full Credit for Main Image: Hemming1952 via Wikipedia under CC By-SA 4.0; John Klavitter / U.S. Fish and Wildlife Service via Wikipedia / Public Domain; Eric Lafforgue / Art in All of Us / Corbis via Getty Images; China Photos / Getty Images; Gianluigi Guercia / AFP via Getty Images; NOAA via Wikipedia / Public Domain

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Source: https://www.smithsonianmag.com/science-nature/from-giant-tortoises-to-immortal-jellyfish-these-impressive-animals-are-eight-of-the-longest-living-species-on-earth-180985577/?utm_source=smithsoniandaily&utm_medium=email&utm_campaign=editorial&spMailingID=50513479&spUserID=MTI1MzcyNjIxNjk1NAS2&spJobID=2824872147&spReportId=MjgyNDg3MjE0NwS2