The animal kingdom boasts some incredibly long lifespans that far exceed the average human's. While humans may have an "absolute limit" of 150 years, this is just a blink of an eye compared with the centuries and millennia that some animals live through; and some animals can even stop or reverse the aging process altogether.
Although there are very long-living land animals (the oldest tortoise, for example, is nearly 190 years old), none of them make this list — the true age champions all live in water. From old to oldest, here are 10 of the longest-living animals in the world today.
1. Bowhead whale: potentially 200+ years old
Bowhead whales (Balaena mysticetus) are the longest living mammals. The Arctic and subarctic whales' exact lifespan is unknown but stone harpoon tips found in some harvested individuals prove that they comfortably live over 100 years, and may live more than 200 years, according to the National Oceanic and Atmospheric Administration (NOAA).
The whales have mutations in a gene called ERCC1, which is involved with repairing damaged DNA, that may help protect the whales from cancer, a potential cause of death. Furthermore, another gene, called PCNA, has a section that has been duplicated. This gene is involved in cell growth and repair, and the duplication could slow aging, Live Science previously reported.
2. Rougheye rockfish: 200+ years old
Rougheye rockfish (Sebastes aleutianus) are one of the longest living fish and have a maximum lifespan of at least 205 years, according to the Washington Department of Fish and Wildlife. These pink or brownish fish live in the Pacific Ocean from California to Japan. They grow up to 38 inches (97 centimeters) long and eat other animals such as shrimp and smaller fish, according to the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), an independent advisory panel that assesses the status of species threatened with extinction in Canada.
3. Freshwater pearl mussel: 250+ years old
Freshwater pearl mussels (Margaritifera margaritifera) are bivalves that filter particles of food from the water. They mainly live in rivers and streams and can be found in Europe and North America, including the U.S. and Canada. The oldest known freshwater pearl mussel was 280 years old, according to the World Wildlife Fund (WWF). These invertebrates have long lifespans thanks to their low metabolism.
Freshwater pearl mussels are an endangered species. Their population is declining due to a variety of human-related factors, including damage and changes to the river habitats they depend on, according to the International Union for Conservation of Nature (IUCN).
4. Greenland shark: 272+ years old
Greenland sharks (Somniosus microcephalus) live deep in the Arctic and North Atlantic oceans. They can grow to be 24 feet (7.3 meters) long and have a diet that includes a variety of other animals, including fish and marine mammals such as seals, according to the St. Lawrence Shark Observatory in Canada.
A 2016 study of Greenland shark eye tissue, published in the journal Science, estimated that these sharks can have a maximum lifespan of at least 272 years. The biggest shark in that study was estimated to be about 392 years old, and the researchers suggested that the sharks could possibly have been as much as 512 years old, Live Science previously reported. The age estimates came with a degree of uncertainty, but even the lowest estimate of 272 years still makes these sharks the longest living vertebrates on Earth.
5. Tubeworm: 300+ years old
Tubeworms are invertebrates that have long lifespans in the cold, stable environment of the deep sea. A 2017 study published in the journal The Science of Nature found that Escarpia laminata, a species of tubeworm living on the ocean floor in the Gulf of Mexico, regularly lives up to 200 years, and some specimens survive for more than 300 years. Tubeworms have a low death rate with few natural threats, such as a lack of predators, which has helped them evolve to have such long lifespans.
6. Ocean quahog clam: 500+ years old
Ocean quahog clams (Arctica islandica) inhabit the North Atlantic Ocean. This saltwater species can live even longer than the other bivalve in this list, the freshwater pearl mussels. One ocean quahog clam found off the coast of Iceland in 2006 was 507 years old, according to National Museum Wales in the U.K. The ancient clam was nicknamed Ming as it was born in 1499 when the Ming Dynasty ruled China (from 1368 to 1644).
7. Black coral: 4,000+ years old
Corals look like colorful, underwater rocks and plants, but they are actually made up of the exoskeletons of invertebrates called polyps. These polyps continually multiply and replace themselves by creating a genetically identical copy, which over time causes the coral exoskeleton structure to grow bigger and bigger. Corals are therefore made up of multiple identical organisms rather than being a single organism, like Greenland sharks or ocean quahog clams, so a coral's lifespan is more of a team effort.
Corals can live for hundreds of years or more, but deep-water black corals (Leiopathes sp.) are among the longest-living corals. Black coral specimens found off the coast of Hawaii have been measured to be 4,265 years old, Live Science previously reported.
8. Glass sponge: 10,000+ years old
Sponges are made up of colonies of animals, similar to corals, and can also live for thousands of years. Glass sponges are among the longest living sponges on Earth. Members of this group are often found in the deep ocean and have skeletons that resemble glass, hence their name, according to NOAA. A 2012 study published in the journal Chemical Geology estimated that a glass sponge belonging to the species Monorhaphis chuni was about 11,000 years old. Other sponge species may be able to live even longer.
9. Turritopsis dohrnii: potentially immortal
Turritopsis dohrnii are called immortal jellyfish because they can potentially live forever. Jellyfish start life as larvae, before establishing themselves on the seafloor and transforming into polyps. These polyps then produce free-swimming medusas, or jellyfish. Mature Turritopsis dohrnii are special in that they can turn back into polyps if they are physically damaged or starving, according to the American Museum of Natural History, and then later return to their jellyfish state.
The jellyfish, which are native to the Mediterranean Sea, can repeat this feat of reversing their life cycle multiple times and therefore may never die of old age under the right conditions, according to the Natural History Museum in London. Turritopsis dohrnii are tiny — less than 0.2 inches (4.5 millimeters) across — and are eaten by other animals such as fish or may die by other means, thus preventing them from actually achieving immortality.
10. Hydra: also potentially immortal
Hydra is a group of small invertebrates with soft bodies that look a bit like jellyfish. Like Turritopsis dohrnii, Hydras also have the potential to live forever. Hydras don't show signs of deteriorating with age, Live Science previously reported. These invertebrates are largely made up of stem cells, which continually regenerate through duplication or cloning. Hydras don't live forever under natural conditions because of threats like predators and disease, but without these external threats, they could be immortal.
Related: When blown apart, hydra re-assemble