In the hidden corners of our planet, some of Earth’s strangest lifeforms are quietly rewriting the rules of mortality.
While most living things march inevitably toward death, these bizarre organisms seem to have found loopholes – some can regenerate entire bodies from a fragment, others can press rewind on life itself and a few can survive extremes that would kill almost anything else.
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Meet the animals that refuse to die...
4 immortal animals that could live forever
Immortal jellyfish
It might not strictly be immortal but this jellyfish (Turritopsis dohrni) is famous as the only animal that, in an emergency, can avert death. This jellyfish may seem little more than a brainless blob the size of a blueberry, but it has the greatest power of all.
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When the medusa (the domed, roaming adult form to which the name jellyfish normally refers) is injured or senses a life-threatening situation, such as starvation, it can revert to the earliest stage of its life-cycle – like a granny morphing back into a baby.
Hydra
Hydras are quite simple creatures, little more than a flexible tube with a mouth at one end, surrounded by a crown of tentacles. They have no heart, brain, eyes or gills.
But their one really weird quality is their powers of procreation and regeneration. Populations can rapidly increase by budding – they simply grow others from their bodies. Perhaps the most bizarre of their talents is the fact they can live forever – if you chop up a hydra, each fragment will form into a separate animal.
Flat worms
There are few pond creatures quite as bizarre as flatworms and it’s their ability to repair and regenerate that truly amazes. A myth about worms, and earthworms in particular is that, if divided, each end will create a new animal. Sadly, it isn’t the case. But it is with flatworms.
Dice a flatworm any which way and each fragment will in time become a fully functional creature. How flatworms do this is not fully understood. But it’s a quality that has given them fame for being, in the words of 19th-century naturalist John Graham Dalyell, “immortal under the edge of a knife”.
Tardigrades
Tardigrades, which translates as ‘slow walkers’, are an eight-legged segmented micro-animal found almost everywhere. They are probably among the most unbreakable creatures on Earth, able to survive dehydration, microwaving and temperatures as hot as 150ºC or as low as –273ºC.
They can also cope with being exposed to the ionising radiation of outer space. Not tough enough? On top of all of these credentials, they can exist in suspended animation for over three decades. It is also claimed that these animals have the physiological capabilities to be the last beast standing in the event of a nuclear holocaust.