There are numerous organisms living on planet earth whose known lifespans far exceed our own. A woman from Arles, France led the longest documented life of any Homo sapien, passing away after an impressive 122 years.
Yet even living over a century cannot compare to the documented longevity found within the animal kingdom. This assortment of animals includes examples from all stages of evolutionary complexity, the simple and the sophisticated, the microscopic to the colossal.
Still, the most astonishing examples of lengthy life occur among some of the least complicated lifeforms, e.g. sponges, corals, and jellyfish. Some of these unassuming creatures are even said to have achieved immortality.
1. DEEP SEA SPONGES (Monorhaphis chuni)- 11,000 years
Sponges are infamous for being slow-growing, but one such species of siliceous glass sponge holds the record for longest living organism on Earth. This deep ocean giant, which can reach nine feet in length, is the sole member of the Monorhaphididae family of sponges. The results of a 2012 study identified one such specimen in the China Sea which was estimated to be around 11,000 years old. Such an estimate puts the deep-sea sponge squarely in first place.
2. DEEP SEA BLACK CORAL (Leiopathes sp.)- 4,000 years
Second place belongs to another deep-sea organism which flourishes at marine depths from 300 to 3,000 meters. Corals are a colonial organism, consisting of numerous, tiny individuals known as coral polyps. Radiocarbon dating has revealed that the lifespan of a black coral colony can exceed 4,000 years. Though the age of the collective colony is considerable, each polyp is typically just a few years old. Such periods of prolonged existence aren’t uncommon amongst corals; colonies of Hawaiian gold coral (Gerardia sp.) were found to reach ages exceeding 2,700 years by the same 2009 study.
3. FRESHWATER HYDRA (Hydra magnipapillata)- 1,400 years
Next is an organism just slightly more complex than sponge and coral, from an evolutionary standpoint. The freshwater hydra known as Hydra magnipapillata is a microscopic relative of jellyfish and sea anemones. What makes this tiny animal remarkable, is that it can live in excess of 1,400 years when grown under optimal conditions. Mortality risks are so minute in the laboratory that 5% of adults with endure more than fourteen centuries.
4. OCEAN QUAHOG aka BLACK CLAM (Arctica islandica)- 507 years
A paper published in 2013 made news after one bivalve was confirmed to be around five centuries old. The Ocean Quahog earned the nickname Ming, named after the Chinese dynasty known to be in power when it was born. Found in cold and frequently deep waters, an individual black clam can be accurately aged by the annual growth increments which form along the shells.
The particular bivalve in question met an untimely death after being dredged up and frozen by researchers as part of a study on climate change. Later its shell was analyzed under a microscope, which led to the discovery of the specimen’s age as approximately 507 years old! Other techniques, such as the carbon-14 method, were used to further confirm the animal’s age.
5. GREENLAND SHARK (Somniosus microcephalus)- 400 years
The first and longest living vertebrate to make the list is the Greenland shark, and it too inhabits the deep ocean waters. One of the largest carnivorous sharks in the world, it is second only to the Great White. The Greenland shark prefers Arctic waters, where it thrives in temperatures ranging from -1°C to 12°C.
A study published in 2016 announced the shark’s potential to live as long as 400 years, with an average lifespan of 272 years. With traditional means of age-determination unsuccessful, researchers utilized radiocarbon dating on the eye lenses of a by-catch sample of females. Amazingly, it was also revealed these sharks only reach sexual maturity after 150 years!
6. BOWHEAD WHALE (Balaena mysticetus)- 133 to 200 years
The bowhead whale is a species which lives year-round in Arctic waters, and is the only mammal to make the list of longest-living animals. Some sources say they can reach 200 years of age. A 2011 publication used length measurements and reproductive data from 50 mature females to uncover a whale approximately 133 years old. An earlier study examined eye lenses in an effort to determine age and found four males over 100 years old.
Previously, rough estimates of age were provided by dating stone harpoon tips and ivory weapon fragments recovered from the bowhead whales harvested by Eskimo hunters. Today, these magnificent 100-ton animals are listed on the IUCN Red List.
7. GIANT TORTOISE (Aldabrachelys gigantean sp.)- ~184 years
Rounding off the list is the only terrestrial (land-dwelling) organism, as well as the only reptile to make the cut. There are multiple species of giant tortoise, all of which have the capacity to reach a remarkable age. In 2014, a Seychelles giant tortoise by the name of Jonathan was estimated to have reached his 182nd birthday.
This makes him significantly older than the infamous Galápagos tortoise Harriet, once the beloved pet of Charles Darwin, who died at the age of 176 years. Although such a lifespan is a far cry from that of the deep-sea glass sponge, it is still more than double the age of an average Homo sapien.
?. IMMORTAL JELLYFISH (Turritopsis dohrnii)
Another animal to merit mention is the immortal jellyfish, a creature who never truly dies. Like Turritopsis dohrnii, many Cnidaria share a common life cycle: an adult medusae produces mobile larva which settle into a colonial polyp stage that then grows to produce new medusa, asexually. In most species, however, the medusae die after sexually reproduction.
Turritopsis dohrnii is an exception; mature medusae will reverse back to the colonial polyp stage when stressed, a stage capable of feeding as well as producing new medusae via budding. These newly released medusae as well as the fully mature individuals are both capable of changing back into colonial polyps when facing stressors such as starvation or physical damage.
A rare process known as transdifferentiation allows adult, somatic cells to become a completely different type of specialized cell. By maneuvering from an adult stage to a simpler, larval stage, this organism escapes death and potentially achieves immortality (as long as it manages to avoid any hungry predators).