No human in history has outrun aging, yet some extraordinary animal species have found ways to stretch the limits of life. They roam the oceans, remain motionless in the deep sea, or wander vast landscapes, defying time in ways that seem almost beyond belief.
A hundred years may feel like a long life for a human, but imagine surviving for several centuries, a thousand years, or even eternity.
Here’s a fascinating look at some of the planet’s longest-living creatures, some of which have outlasted entire human civilizations.
Read More: Meet The Longest Living Animal Whose Birth Predates Shakespeare
The Longest-Living Animal Ever Recorded: The Glass Sponge
Image credits: NOAA
The ocean harbors a vast world of seemingly eternal dwellers. Among them are the glass sponges in the class Hexactinellida, also known as the longest living species on the planet (per International Fund for Animal Welfare). These super endurers are often found in the deep waters and have long fascinated scientists with their survival methods.
The tissues of these deep-ocean dwellers feature structural particles called spicules, which are made of silica and resemble glass (per the National Ocean Service).
Certain glass sponge species can produce massive spicules that join together to form what is aptly named the “glass house.” This intricate, sturdy skeleton withstands environmental changes, often remaining intact well beyond the death of the sponge itself.
The glass sponge’s secret for longevity lies in its skeleton and other chemicals that shield it from life-threatening predators. In fact, many sea creatures call their protective skeleton home.
Glass sponges spend their long lives attached to hard surfaces, filtering small bacteria and plankton from the surrounding water to fuel their bodies.
Scientists long believed that glass sponge reefs had gone extinct 40 million years ago, with only their massive fossil remains scattered across France, Spain, Germany, and Romania.
That belief was overturned in 1987 when a team of Canadian scientists discovered a thriving, 9,000-year-old living glass sponge reef, the first ever seen (per Ocean Conservancy).
Image credits: NOAA
The scientists, who discovered British Columbia’s northern coast, likened it to “finding a herd of dinosaurs wandering around on land.” No other reefs like that are known to exist today.
Among all species of glass sponges, the Venus’ flower basket (Euplectella aspergillum) stands out as one of the most fascinating. Shaped like a delicate vase or cylinder, this sponge forms a skeletal lattice that traps small crustaceans inside.
What unfolds is an unexpected shrimp love story. A pair of tiny boxer shrimps (Stenopodidea), one male and one female, make their home inside the sponge. There, they mate and raise offspring, which leave while still small to find a Venus’ flower basket of their own.
The shrimp, in turn, provide a cleaning service for the sponge, helping keep it clear of debris, while the sponge provides food by capturing organic waste. As the pair grows, they eventually become too large to leave, destined to remain inside the sponge for the rest of their lives.
While adult glass sponges like the Venus’ flower basket are “sessile,” meaning they stay fixed in place, other long-lived ocean creatures roam freely through the deep, dark waters (per University of Hawaii at Manoa).
Greenland Sharks: The Longest-Lived Vertebrates on the Planet
Image credits: @pdemaagt
The fearful Greenland sharks have long sparked scientists’ curiosity. They suspect these heavy-set fish have an exceptionally long lifespan, but have fallen short of measuring their exact age (per the National Ocean Service).
This long-standing mystery was solved with the help of cutting-edge carbon dating. The secret to the shark’s remarkable longevity lies in its eyes, where proteins formed before birth remain unchanged as the shark ages, almost like a fossil perfectly preserved in amber.
Image credits: NOAA
Carbon-dating these proteins makes it possible to determine the previously unknown age of Greenland sharks. The breakthrough method revealed that Greenland sharks can live at least 250 years (and may even live up to 500 years), making them the longest-lived vertebrates.
While no single Greenland shark is individually tracked today, scientists now know that they live for centuries, a record-breaking longevity that can be attributed to slow growth, movement, and metabolism.
Giant Tortoises: The World’s Oldest Living Terrestrial Animals
Image credits: Matthew Field
Giant tortoises are among the longest-living land animals in the world. These majestic reptiles are rightfully the largest tortoises on earth, with some specimens standing as tall as five feet and weighing as much as 500 pounds (per National Geographic).
Their secret for longevity? Slow living.
Adult humans’ normal resting heart rate ranges from 60 to 100 beats per minute, with lower rates generally indicating better cardiovascular health (Harvard Health).
In contrast, giant tortoises have an astonishingly low heart rate of about 14–25 beats per minute, according to a 2019 study published by the National Center for Biotechnology Information, which evaluated four giant Aldabra tortoises. Some experts believe these remarkable animals may have a lower resting heart rate.
“Tortoises only have three heartbeats per minute, the slowest heart rate of any animal in the Galápagos,” said Ballestros, a naturalist guide in the Galápagos Islands (per Canadian Geographic).
Image credits: Michael Kuhn
This remarkably slow pace of life directly contributes to their longevity. The world’s oldest known land animal is Jonathan, a Seychelles giant tortoise believed to be 192 years old.
Jonathan was born when Queen Victoria was still a teenager or possibly earlier. “Jonathan could be 200 because the records of his arrival on the island are unclear, and there’s no official record of his birth,” Matt Joshua, head of tourism on St. Helena, told CNN.
This kind of rough estimation isn’t unusual. In 2006, Addwaita, an Aldabra tortoise at the Calcutta Zoo, died at an estimated age of 250 (per CBC News).
Addwaita’s name, meaning “the one and only” in Bengali, reflected his legendary status and lifespan across much of India’s modern history. He first arrived at the zoo in 1875.
For perspective, Addwaita outlived Harriet, the famed 176-year-old Galápagos tortoise once housed at the Australia Zoo.
Turtles share similar survival superpowers. “Think of these lower animals as living longer because their pilot light is lower. They’re not 37 degrees [Celsius], they’re not racing around,” said Kenneth Storey, a professor at Carleton University who studies turtles (per Business Insider).
“They’re not burning the candle at both ends, they’re barely burning the candle at one end, and during anoxia they stop burning the candle. That’s how they can live so long. It’s a pace argument.”
The “Immortal” Jellyfish that Will Theoretically Live Forever
Dying is inevitable for most living creatures, but the Turritopsis dohrnii, fittingly nicknamed the “immortal jellyfish,” has found a way to defy death.
This remarkable species was first discovered in the Mediterranean Sea in 1883, but it wasn’t until nearly a century later that scientists accidentally uncovered its astounding ability to bypass aging (per the Natural History Museum).
The Turritopsis dohrnii begins life like any ordinary jellyfish: a tiny larva called a planula, which develops from a fertilized egg. The planula swims freely at first before settling on the sea floor, transforming into a colony of polyps. These polyps eventually produce the adult jellyfish, known as medusae, within just a few weeks.
Before the surprising discovery, students Christian Sommer and Giorgio Bavestrello collected Turritopsis polyps and carefully observed them until they released medusae.
Based on what was known about jellyfish then, the medusae were expected to mature, spawn, and eventually die. But to the scientists’ astonishment, when they checked the jar, they found numerous newly settled polyps, revealing the jellyfish’s astonishing ability to reset its life cycle and effectively escape death.
Under stress, these remarkable jellyfish behave in astonishing ways. A 1992 study published in the Scientia Marina Journal found that the medusae would sink to the bottom of their containers and transform into polyps. This transformation bypasses fertilization and the usual larval stage, earning Turritopsis dohrnii its reputation as the “immortal jellyfish.”
Naturally, this groundbreaking discovery sparked the intense curiosity of scientists worldwide. A 2024 paper published in the Proceedings of the National Academy of Sciences highlighted Turritopsis’s extraordinary ability to remain effectively ageless despite environmental pressures.
“To date, Turritopsis dohrnii is the only known species capable of undergoing reverse development after the onset of sexual reproduction,” the study notes.
It also points to another surprising finding: the comb jelly (Mnemiopsis leidyi) can revert from its mature lobate form to the earlier cydippid stage under stress.
“The work challenges our understanding of early animal development and body plans, opening new avenues for the study of life cycle plasticity and rejuvenation. The fact that we have found a new species that uses this peculiar ‘time-travel machine’ raises fascinating questions about how widespread this capacity is across the animal tree of life,” study co-author Joan J. Soto-Angel told Phys.org.
This biological “time-travel” phenomenon opens the door to deeper insights into life, aging, and death, and may even spark fresh intrigue around the long-standing human dream of immortality.
“Witnessing how they slowly transition to a typical cydippid larva, as if they were going back in time, was simply fascinating,” Soto-Angel added.
“Over several weeks, they not only reshaped their morphological features but also adopted completely different feeding behavior, typical of a cydippid larva.”
The Mystery of Aging Still Puzzles Scientists
Image credits: Alexas_Fotos
Why can some animals bend the rules of life while others, including humans, can’t? And most intriguingly, why do humans, with all their intelligence, still fail to escape the typical cycle of life and death?
The survival secrets of the world’s longest-living species are explored in the book “Methuselah’s Zoo: What Nature Can Teach Us about Living Longer, Healthier Lives” by Steven N. Austad, a Distinguished Professor and Protective Life Endowed Chair in Healthy Aging Research at the University of Alabama (per UAB).
Ultimately, how long we live comes down to one key factor: our ability to self-repair. In other words, human longevity depends on how effectively we can repair and replace damaged cells.
And the scale of this challenge is staggering: every day, internal processes create enough stress to damage the DNA in our cells at least 10,000 times.
While our bodies manage to repair some of this DNA damage daily, our repair systems fall short over time. Humans don’t have the planet’s most advanced or efficient repair and replacement mechanisms compared to other long-lived species.
Image credits: Vien_beos
For example, why do humans develop cancer while elephants, with lifespans similar to ours, rarely do? Despite having around sixty times more cells, each with the same potential to become cancerous, elephants appear to have evolved roughly sixty times better cancer resistance than we have.
When it comes to longevity, size matters. We’re smaller than elephants, but we’re larger than dogs, cats, or mice, which helps explain why we typically outlive these smaller creatures.
The reason is simple: smaller species live in overdrive, racing through growth, reproduction, and survival, ultimately shortening their lifespans.
“I think it’s all about energy: energy use, energy storage, and the type of pathways that are being engaged to derive energy,” said Rozalyn Anderson, an associate professor at the University of Wisconsin School of Medicine and Public Health (per Business Insider).
Of course, scientists are still far from fully cracking the code of aging. “To me, aging is the most compelling issue in modern biology. It’s surprisingly complex,” said Christopher Wiley, a scientist with the Basic Biology of Aging Team (per Tufts Now).
“There are so many ways of getting at the same problem. There’s always going to be something new to figure out and something new to study.”