Oct 22, 2025
By: Isha AgarwalKnown as the “immortal jellyfish,” this tiny marine creature can technically live forever. When faced with stress or injury, it reverts back to its juvenile stage and starts life anew, a process called transdifferentiation. It’s nature’s closest example to biological immortality.
Found in the cold, deep ocean, glass sponges are among the oldest living organisms on Earth. Some species have been dated to over 10,000 years old, surviving by filtering microscopic food from seawater. Their silica skeletons are what make them so durable and long-lived.
The rougheye rockfish, native to the Pacific Ocean, is known to live more than 200 years. Slow-growing and deep-dwelling, this species thrives in icy waters where metabolism slows, helping it live longer than most vertebrates.
These beautiful ornamental fish are symbols of luck and longevity, especially in Japan. While most koi live 25–40 years, one famous koi named Hanako lived to be 226 years old, making it one of the longest-living fish ever recorded.
The bowhead whale, found in Arctic and sub-Arctic waters, can live over 200 years, making it the world’s longest-living mammal. Their slow metabolism and frigid habitat contribute to their extraordinary lifespan.
The Greenland shark is one of the oldest known vertebrates on the planet, with lifespans estimated at 250–500 years. These massive, slow-moving sharks live in icy Arctic waters and don’t reach maturity until around 150 years of age.
Unlike the corals we see in shallow tropical reefs, black corals live deep in the ocean and grow incredibly slowly. Some colonies are estimated to be over 4,000 years old, making them ancient witnesses to Earth’s changing climate.
This clam species can live for 500 years or more, with one specimen named “Ming” recorded at 507 years old. Their slow growth in cold waters helps them survive through centuries of environmental change.
The red sea urchin, native to the Pacific coast of North America, can live up to 200 years in the wild. Despite their simple structure, their slow metabolism and regenerative ability contribute to their long lives.
Though tortoises are already known for longevity, the Aldabra giant tortoise deserves mention — some have lived more than 150 years. Their calm lifestyle and slow metabolism make them one of nature’s most enduring creatures.
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