These 4 animals live so long that they are considered immortal

The innumerable varieties of flora and fauna around the world are not only amazing but also interesting because of their unique individual characteristics. There are some species, who, to our dismay, live for a very short span of time while there are others who live for so long that they are often mistaken to be immortal. For example, bowhead whales live as long as 200 years. However, this is also nothing in comparison to certain organisms that live for thousands of years, while humans only make it to an average of 72 years according to the World Health Organization (WHO). The entire science community is trying their best to solve the mysteries behind this high life expectancy of certain species, in the hope of using that knowledge to expand the lifespan of humans. Here is a broad overview of four longest living species on earth.  

Turritopsis dohrnii 
This jellyfish species, apparently lacks two most important organs of any animal’s body: Brain and heart. According to biologists, such jellyfish don’t turn old and die like almost all other living beings. They simply live up to a certain age and then start getting younger, finally going back to their original state of glory. Their lifespan simply follows a vicious cycle, young to old and back to young again. However, researchers are yet to know exactly why these jellyfish replenish on their own. These species that survive in tropical waters only occasionally die due to illness or predators.  

Antarctic Sponge 
The Antarctic Sponge has made its name in the Guinness Book of World Records for its incredible longevity. This happens predominantly due to their excessively slow growth and cold natural habitat. One of the very few companions of the penguins, Antarctic Sponge lives in the polar climate of the world’s coldest continent Antarctica. It is presumed to live as long as 5000 to 15000 years, by simply reducing their degree of metabolism. This sponge grows only 0.2 mm in length annually, and lives 200m under ice cold water, where sunlight can’t enter. 

Giant Galapagos Tortoise 
The Galapagos Island has been famous for being the chosen habitat for some of the world’s most unique creatures. You can take the critically endangered pink iguanas for example. These Algebra species are among the longest living vertebrates, their average life expectancy being similar to the bowhead whales, i.e., 200 years. Although typical of this archipelago region, one male member of this species was imported by the Kolkata Zoo authorities and was reported to have died in 2006 at the age of 255. They weigh around 250 kgs and their average lifespan ranges from 150-250 years. Legend says that one of the male tortoises of this particular species was once in possession of Lord Clive, the British dictator in India.  

Greenland shark 
Found deep underwater in the Arctic Ocean, the Greenland sharks belong to the family of somnios. Just like Antarctic sponge, they have high life expectancy for the very same reasons: Cold habitat and slow growth rate (0.5 to 1cm annually). These are the only shark species that can bear with the Arctic climate that ranges from 7 to minus 22 degrees. Marine biologists consider this to be a mysterious phenomenon since most sharks are thermophilic. These 24 feet long animals live for 150 to 200 years, longest for any shark species. Till date, the longest any of these sharks lived for, was 392 years. Scientists often call Greenland sharks the longest-living vertebrate animal. Research still continues using radiocarbon on their eyes to further the knowledge about them.