The Oldest Known Living Organisms In The World

BBC.Jonathon the giant tortoise may be the world's oldest vertebrate

Among the world's living things, humans get a better go than most. To mayflies or perennial plants 70 years would seem an unimaginable length of time.  However, there are some living things for whom we are just a brief, and possibly annoying, blip.

Jonathon is a Seychelles giant tortoise (Aldabrachelys gigantea) residing on St Helena who is still plodding along at what is believed to be the age of 182. This makes him possibly the oldest living land animal, and a strong contender for oldest vertebrate. While this claim is unconfirmed, Jonathon was full sized in the 1880s and giant tortoises are known to have lived to at least 188, so the claim has some credibility.

The image proving Jonathon was fully grown by 1900

However, it is certainly possible that there are older animals out there in the wild. Besides giant tortoises on remote islands with no predators to fear, a likely contender for Jonathon's title of oldest land animal would come from the tuatara (Sphenodon punctatus and S. guntheri). These two species, unique to New Zealand, are old in another way, with many characteristics unchanged for 220 million years. However, no one knows just how long individual tuatara live – one male bred for the first time at 110 and there is speculation they may live to 200 given the chance.

In the ocean, some animals manage to live much longer. The beautiful corals of tropical reefs seldom live longer than 400 years, but deep sea black corals are a different story. The longest lived Leiopathes measured have been found to be 4265 years old. Given how much of the deep sea is unexplored there are almost certainly older specimens out there.

Some studies suggest Antarctic sponges may be over 10,000 years old. Having no brains, nervous or circularity system probably helps the time go past. However, these estimates are based on assumptions about growth rates, which have been thrown into question with the finding of a community of glass sponges beneath what was once the Larsen Ice shelf growing at astonishing rates.

Plants have us animals beat. The oldest individual tree identified is a Giant Basin Bristlecone Pine (Pinus longeva), which at 5064 has more than 200 years on its nearest rivals.

Rachel Sussman. The oldest macroscopic, non-clonal specimens on Earth are Bristlecone Pines. 

Some plants have found a way to do better. Clonal plant colonies are formed from genetically identical specimens. Often connected through the root system, individual parts will grow and decay, but the organism as a whole goes on. The most extreme example identified is a stand of quaking Aspen (Populus tremuloides) in Utah nicknamed Pando, thought to be 80,000 years old. As the National Parks Service puts it, “Aspen are so different that it may be better not to think of them as trees. A stand of aspen is really only one huge organism where the main life force is underground.”

Prando, captured by Rachel Sussman as part of her study of the oldest living organisms.

You might think that this is cheating – if no one trunk stays alive more than a few hundred years, is it really the same organism? However, the cells in your body also grow and die. The fact that most of the cells you have now are different from the ones you had when you were twelve doesn't make you a different person. The analogy is imperfect, but might help explain why the stand is taken to represent the oldest living plant, even when individual parts are quite young. If you don't want to bother with DNA testing, a colony can be told from its neighbors by the timing of when its leaves change color.

Pando, under threat from global warming and overgrazing, is also considered the heaviest organism in the world (six thousand tonnes!) but fungal colonies might pose a challenge to the age record. It is hard enough to estimate the age of clonal tree colonies – clonal funguses are harder still. While the officially recognized estimate for a giant Armillaria bulbosa, dubbed the humungous fungus, is a youthful 1500 years, there is speculation this or other fungal colonies may be older than Pando.

Of course, if you are looking for really old lifeforms you need to consider whether it is a requirement they have to have been functioning all that time. Seeds buried in permafrost for more than 30,000 years have been grown to fertile plants.

The ultimate survivors, however, are probably the much less spectacular bacterial spores. Having developed the capacity to shut down all activity while they wait for water or warmth to come again, some bacteria find themselves in suspended animation far longer than anyone would expect.

For his PhD Dr Brian Schubert of the University of Binghamton revived Dunaliella bacteria that had been buried in salt in Death Valley for 34,000 years. While this is still younger than Pando, controversial claims for much longer – in one case 250 million years – revivals have been made. Whether these are true or not, it is hard to credit that lifeforms that can survive for 30,000 years can't do so for three or ten times as long, even if we have no idea how they restore the inevitable DNA decay. Meanwhile, bacteria collected from the Siberian permafrost appear to have survived, without dormancy, for half a million years.

The bacterial spores, stained with Beta carotene Brian Schubert revived after 34,000 years.

Finally, its worth saying a word about “immortal” jellyfish. Turritopsis dohrnii has an astonishing capacity to rise phoenix-like, “Escaping death and achieving potential immortality,” in the words of the scientists who discovered this talnet, by returning to the polyp stage. Nevertheless, it is unlikely that any jellyfish has lived for anything like as long as Jonathon, let alone Pando – there are simply too many predators and other dangers to allow it to restore itself the hundreds or thousands of times that would be required to win a place on this list.

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