Humans have been trying to extend their lifespan for millenia, basically as long as humans have existed. However, certain animals can live for centuries without even trying. Scientists attribute their longevity to the animals’ metabolism. Metabolic rate is considered to be inversely related to lifesan, so those with a slow metabolic rate will live longer, while those with a fast metabolism will tend to live shorter lifespans.
Here’s a list of the top 5 animals with the longest lifespan.
#5: Greenland shark (Somniosus microcephalus): 300-500 years
Greenland sharks live in the Arctic and North Atlantic oceans. Often referred to as “dinosaurs on earth,” they can grow up to 24 ft/7.3 m long, and are the longest-living vertebrate. These sharks move and grow very slowly, only growing about 1 cm per year.
Scientists determine the ages of Greenland sharks by looking at their eye tissue: new tissues are added to the eye lens every year, and this tissue can be carbon-dated to estimate the age of the shark.
#4: Ocean quahog clam (Arctica islandica): 500+ years
These clams live in the North Atlantic Ocean, and often survive for over 400 years. The oldest ocean quahog, named Ming because it was born during the Ming dynasty’s rule of China, was found to be 507 years old. The ocean quahog has an extremely slow metabolism, which is why it can survive for such a long time. Scientists even believe that the ocean quahog can live to be older than 507. The ages of clams are calculated by counting the lines on the shell, similar to counting rings in a tree trunk.
#3: Black coral (Leiopathes glaberrima): 4,000+ years
Corals may look like plants, but they are actually made of small animals called polyps, which continuously multiply to keep building the coral. Thus, a coral’s lifespan isn’t dependent on a single organism, but rather many small ones working together. Usually, black coral colonies live for around 70 years. However, in 2009, a deep-water species of black coral was discovered off the coast of Hawaii, estimated to be around 4,265 years old.
#2: Glass sponges (Class Hexactinellida): 10,000+ years
Like coral, sponges consist of colonies of small animals. Sponges have a very long lifespan, with glass sponges among the longest-living. Glass sponges are found in extremely deep areas of the ocean and have glass-like appearances. They come in a range of shapes and sizes, and are attached to the sea floor.
The glass sponge was thought to have gone extinct around 40 million years ago, but scientists discovered some in Canada in 1987, which are the only glass sponges remaining today (that we are aware of).
#1: Immortal jellyfish (Turritopsis dohrnii): potentially immortal
As the name suggests, immortal jellyfish may live forever – and are currently the only creatures that scientists believe are able to. Jellyfish start their lives as larvae called planula, before attaching to the seafloor and becoming polyps. These polyps are what will become jellyfish.
What makes the immortal jellyfish unique, however, is that they can turn themselves back into polyps if they are injured or starving, and return to their mature state later. Essentially, they are reversing their life cycle and may never die of old age. Unfortunately, they are extremely small (0.2 in/4.5 mm across) and are often eaten by other animals.