Imagine a person had to have a leg amputated and then that lower limb hopped off to lead a life of its own, fighting off infection and reorganising its cells to work without the rest of the body. That would be the plot of a dodgy horror movie, wouldn’t it?
Not if you’re a Psolus fabricii sea cucumber.
These soft little animals, clinging to rocks in the Atlantic and Arctic oceans with tiny tube feet, have a creepy talent. Any part of their body torn off by accident or by a predator – a leg or delicate feeding tentacle – does not die. It lives on as a zombie.
- Masters of regeneration: these death-defying animals can regrow body parts better than Deadpool
- "They're able to regenerate their bodies from tiny fragments..." Why some animals have abilities that rival the 'healing powers' of Deadpool or Wolverine
Tissue regeneration in some species generally works the other way round. A salamander that loses a leg or a tail can grow another one. A lobster will regrow a missing claw and a sea star an arm. But the bit that comes off – assuming it hasn’t been eaten by something, of course, will just lie where it was discarded and rot away.
With P fabricii scientists have observed its dismembered bits living on, sometimes for more than three years after separation, absorbing amino acids and nutrients from the saltwater to keep tissues alive and cells dividing. These characteristics count as valid proof of life, although maybe not as we humans know it.
The process of repair and subsequent independent living of the lost sea cucumber parts was completed in less than six days after the leg or tentacle was ripped away. The torn and ragged edges of the wound immediately began to shrink and heal and the undamaged tissue curled inwards to seal the open gap. The same process was meanwhile happening at the original site of the limb, preparatory to the animal growing a replacement.
- Cordyceps and Orphiocordyceps: the zombie fungi made famous by The Last of Us
- It not only eats its victim from the inside out, it also uses a biological weapon to paralyse it and turn it into a zombie
It is the capacity to clean away any damaged tissue that might be vulnerable to bacteria, and therefore prone to infecting the rest of the healthy tissue and killing it, that is one aspect of the study fascinating scientists.
They observed the biological sequence known as apoptosis, or cell suicide, taking place in the severed parts. This is the mysterious process of systematic elimination of unwanted cells that happens in all living organisms but had not previously been seen in seemingly dead tissue separated from its host.
Another surprising discovery awaited the researchers as they monitored the progress of the sea cucumbers’ amputated body parts.
Although living, the tube feet remained motionless at the site of their separation from the body for the rest of their natural life span. However, the tiny outgrowths of excised tentacles were seen to move around in response to being poked, showing that some muscle regeneration had occurred along with just the body tissues, and that neural networks had been preserved.
All of these observations are feeding into the study of body part regeneration in general and its ability to survive long-term. The findings will assist biomedical research and tissue engineering experiments, which will benefit work to replace diseased and damaged human flesh.
The plan, of course, will be to keep this so-called immortal tissue as part of the original body, not allow it to zombie its way in the world on its own as the sea cucumber unwitting does!
- 12 weirdest body parts, including fake penises, creepy extra-long fingers – and a moth with an extraordinary 30cm long tongue...
- Meet the immortal animals that never die
- 4 animals that can cheat death again and again: Meet the creatures that refuse to die...
Top image: An armoured sea cucumber (Psolus fabriciiredit: Rebecca Evans, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons) observed off Nain, Labrador, Canada.
