The living dead may be lurking beneath the deep blue sea.
Scientists have discovered an aquatic creature that they’re calling a “real-life zombie” — with tissue that can survive and function on its own for years after being severed from the original animal.
The bizarre finding, researchers say, raises questions about what it really means to be “alive” and could have major implications for humans.
In the study, a team of Canadian scientists focused on an animal called Psolus fabricii.
Better known as the scarlet sea cucumber, this marine invertebrate inhabits the frigid waters of the North Atlantic and Arctic.
Just as lizards can regrow tails and starfish can sprout new arms, sea cucumbers have impressive healing abilities, capable of replacing major body parts, including internal organs.
“We’ve always known that sea cucumbers can regenerate remarkably well, but the assumption was that any detached tissue would simply die,” Sara Jobson, who led the research team, said in an interview with Memorial University’s Gazette.
But a chance mishap in the lab would challenge that long-held belief.
One day, a researcher was removing a Psolus fabricii from its tank when some of its tube feet — tiny appendages the animals use to move along the seafloor — broke off and stuck to the glass.
Rather than dying, the detached pieces appeared to remain alive.
Intrigued, the team decided to investigate further. Researchers removed additional sections from the animal’s tube feet, body and tentacles, then placed the fragments in flowing natural seawater.
The water was teeming with microbes, where detached tissue would normally be expected to break down.
But instead, the fragments began healing themselves. Within days, their wounds had closed, while their cells continued dividing and reorganizing.
The tissue also showed signs of immune activity and metabolic function — meaning it was still carrying out the basic processes needed to stay alive.
Upon closer examination, the researchers found that the fragments appeared to be absorbing amino acids directly from the seawater, essentially taking in nutrients without a mouth.
“Natural seawater is just about the most microbially diverse, least clean approach we could take experimentally,” Rachel Sipler, a senior research scientist at Bigelow Laboratory for Ocean Sciences, said in a press release.
“Yet, that rich environment full of bacteria and all this organic matter was actually feeding them and allowing this tissue to heal and grow.”
The fragments didn’t grow into entirely new sea cucumbers or reproduce. Instead, they continued functioning as independent pieces of living tissue.
And they kept at it for more than three years. Researchers eventually ended the experiment so they could publish their findings — but even then, the tissue showed no signs of aging or decay.
“We haven’t grown a new, complete sea cucumber yet, but we are seeing pretty stunning growth and diversification of cells literally years after this tissue was removed,” Sipler said.
“It’s like a lizard that loses its tail. We know some lizards can grow new tails; we’re talking about whether the tail can grow a new lizard.”
The team wanted to see if the same thing would happen with other animals known for their ability to regenerate, so they tried the experiment on sea stars and sea urchins, too.
But tissue taken from those creatures broke down within weeks or months.
That suggests Psolus fabricii may possess some unusual biological capabilities that allow its detached tissue to stay alive long after being separated from the rest of its body.
The findings “challenge the boundary between organismal life and cellular autonomy,” the study authors wrote, “compelling a redefinition of what it means for tissue to be alive.”
The scientists say their discovery could one day have implications for human medicine.
Understanding how the sea cucumber’s tissue manages to survive, heal and keep functioning for years could help inform future research into tissue repair, wound healing and cellular aging.
For now, the next step is to take a closer look at the cells’ DNA to determine whether they show signs of aging as they continue to multiply.
“That would confirm whether or not they are truly immortal,” Jobson told CNN.
