The short answer: Animals that live for centuries do not appear to share one master longevity switch. A new review of 101 species with maximum lifespans of at least 250 years points instead to overlapping strategies: maintaining DNA, tolerating stress, preserving regenerative cells and controlling cancer. The evidence is intriguing, uneven and spread across very different branches of life.
A club with very few animals
The review began with an arresting list. Among 101 multicellular species reported to reach 250 years or more, 90 were plants and only 11 were animals. The animal members include slow-growing creatures from cold or stable environments, as well as organisms with forms of regeneration that have no close human equivalent.
The ocean quahog, Arctica islandica, can reach about 507 years. Greenland sharks have been estimated to live as long as 392 years. Some sponges and corals may persist far longer. Hydra and the jellyfish Turritopsis dohrnii are sometimes described as potentially immortal because they can continually renew cells or return to an earlier developmental state, although they can still die from predation, infection or environmental change.
Maximum lifespan is also not the same as a typical lifespan. It usually describes the oldest verified or estimated individual, and the certainty of those estimates varies widely. A long-lived species may spend much of life growing slowly in a protected niche, while another relies on continuous regeneration. Putting them on one chart does not make their biology interchangeable.
1. Keeping the genome usable
Every long life creates repeated opportunities for DNA damage. Radiation, reactive molecules, copying errors and ordinary metabolism can all damage genetic material. If repair fails, cells may malfunction, die or become cancerous.
Across several long-lived lineages, researchers have found expansions or altered activity in genes involved in DNA repair, chromosome maintenance and the response to damage. Long-lived bivalves show evolutionary changes in pathways involving repair, protein homeostasis, hypoxia and apoptosis. The so-called immortal jellyfish has additional copies of genes linked to DNA replication, repair and oxidative-stress control compared with a related species that lacks the same rejuvenating life cycle.
These are clues, not a universal recipe. More copies of a gene do not guarantee more of the corresponding protein or better repair. Many comparisons include only a few species, making it difficult to separate longevity biology from adaptations to temperature, habitat or reproduction.
2. Surviving stress without destroying the tissue
Long-lived organisms must handle heat, cold, low oxygen, infection, protein damage and metabolic by-products for unusually long periods. The review found recurring evidence for stress-response systems, including antioxidant defenses, protein folding, mitochondrial maintenance and pathways that decide whether a damaged cell repairs itself or dies.
Yet simple antioxidant stories do not hold up well. Greenland sharks did not show obviously higher levels of one antioxidant enzyme than shorter-lived vertebrates. Among ocean quahogs, differences in metabolic rate and several oxidative-stress measures did not clearly explain why one population outlived another.
The lesson is less about possessing one powerful antioxidant and more about maintaining coordinated damage control. Preventing damage, repairing it, removing damaged components and avoiding chronic overreaction may all matter.
3. Preserving stem cells and regeneration
Some animals solve tissue maintenance through extraordinary renewal. Hydra continually replace their cells. Planarian flatworms maintain mobile stem cells called neoblasts that can generate every major cell type and rebuild large parts of the body. Some sponges, corals and jellyfish also preserve regenerative capacity that would be remarkable in a mammal.
The transcription factor FoxO has been linked to stem-cell maintenance and regeneration in hydra. In planaria, DNA repair and familiar growth-control pathways help coordinate continuous cell division.
Humans also depend on stem cells, but our organs are more structurally specialized and our regenerative programs are tightly constrained. Turning up cell division indiscriminately would raise the risk of abnormal growth. The longevity problem is therefore not simply how to regenerate more, but how to preserve repair without losing control.
4. Suppressing cancer over a long life
A centuries-long lifespan gives mutations more time to accumulate. Long-lived organisms must somehow manage that risk.
The review highlights enhanced tumor-suppression and cell-death pathways in several species. Tumors appear uncommon in ocean quahogs and freshwater pearl mussels, while planaria combine continual regeneration with strong control of stem-cell proliferation. Plants use a different architecture: rigid cell walls and compartmentalized growth can limit the spread of abnormal cells.
The evidence base is incomplete. A species with few recorded tumors may simply be poorly studied. Hydra can develop spontaneous tumors in laboratory colonies, and exposure to carcinogens can produce tumors in planaria. Extreme longevity does not make an organism invulnerable to cancer.
Why telomeres and metabolism are not enough
Telomeres protect chromosome ends, and critically short telomeres can limit cell division. They matter, but the review found no consistent relationship between telomere length or telomerase activity and lifespan within every extremely long-lived species. In ocean quahogs, neither measure clearly explained population differences. In ancient bristlecone pines, telomere patterns differed among roots, needles and core tissue.
A low metabolic rate is also an incomplete answer. Cold, slow-growing animals often live a long time, but metabolism did not explain all lifespan variation within ocean quahog populations. Environment can contribute without being a universal cause.
What these species can teach us
Comparative biology is useful because evolution has already run many experiments. If unrelated long-lived species repeatedly strengthen genome maintenance, stress control, regeneration and cancer suppression, those convergent themes can point researchers toward promising questions.
They do not provide ready-made human treatments. A pathway that helps a clam survive for five centuries in cold water may not be safe to activate in a warm-blooded mammal. A hydra’s body plan and continuous cell turnover are far removed from a human brain or heart. Even apparently shared genes operate inside different physiological systems.
The review itself notes that molecular data are sparse and inconsistent across the 101 species. Plants greatly outnumber animals in the list, and some organisms have been studied far more intensively than others. The apparent common denominators should therefore be treated as hypotheses for comparative testing.
The Lifespan Brief answer
Some animals live for hundreds of years because evolution has assembled multiple ways to preserve function: better maintenance of DNA and proteins, resilient responses to stress, durable regenerative cells and safeguards against cancer. Different species weight those strategies differently.
There is no single longevity mechanism waiting to be copied into people. The more realistic opportunity is to learn how long-lived organisms balance repair with restraint, then test whether parts of that balance can improve human health without introducing new risks.
Primary source
How to live for centuries: common denominators of organisms with exceptional longevity, Aging, September 2026.