A piece of sea cucumber refused to die - and lived apart from its body for more than three years

It sounds like a science fiction story, but this is a real experiment. Scientists studied tissues of the cold-water sea cucumber Psolus fabricii and found that individual fragments of its body can remain viable outside the body for a long time. The work was published in Science Advances.

Important: the researchers did not grow a new sea cucumber from a severed piece. It's not about the "immortality" of the animal, nor is it a ready-made technology for medicine. But the very ability of the tissue to live, heal and change for years without a body was so unusual that it may become a new model for studying regeneration.

Details

Sea cucumbers have been known before for their powerful ability to regenerate. Some species can discard internal organs when threatened or severely stressed, and then regrow them anew. So biologists have long viewed sea cucumbers as convenient models for studying tissue and organ regeneration.

But the new study is about something else. Scientists observed not tissue regeneration inside a living animal, but individual fragments that had already been removed from the body. They studied tissue from the tubular legs, body and tentacles of three individuals of Psolus fabricii.

Normally such fragments should break down quickly, especially if they are not in a sterile laboratory environment. But some of the specimens in natural seawater did not disintegrate. The tissues closed the lesions, maintained structural integrity, and showed cellular activity and signs of remodelling.

The most surprising thing was the conditions. In classical laboratory cultures, cells are often grown in a strictly controlled and sterile environment. Here it was different: the samples lived in ordinary, non-sterile seawater, where there are bacteria, organics and other microorganisms. According to the study repository, the separated epidermal, connective, nerve and muscle tissues healed and continued to grow in natural non-axenic seawater without additives for more than three years.

The researchers speculate that the tissues may have derived nutrition from dissolved organic matter, such as amino acids, in the water. This makes the finding particularly interesting: the tissue was not just "preserved" but continued to behave like a living system.

Why it's important

The main value of the discovery lies in the ability to better understand how tissues heal and remain viable. If scientists can figure out why sea cucumber fragments don't die for so long, it could help research into regeneration, wound healing, cellular stability, and tissue-microbial interactions.

But medical conclusions should be cautious for now. We can't say it will soon allow people to grow organs or limbs. There is a huge distance between marine invertebrate tissue and human medicine.

But such a model could be useful for basic science. Sea cucumbers are invertebrates, so working with their tissue is ethically and organisationally easier than with vertebrate or human tissue. If the method is validated and reproducible, it could become an affordable tool for laboratories that study healing and regeneration.

Background

Sea cucumbers belong to the echinoderms, the same large group of animals as starfish and sea urchins. Many echinoderms are known for their unusual tissue repair abilities. For example, the regeneration of the gut and other organs after internal structures have been damaged or discarded is well studied in sea cucumbers.

The new study is different in that it shows the long life of tissue already outside the body. This brings the work closer to the topic of "immortal" cell lines, which scientists have been using for decades, but here we are not talking about individual cells in a sterile environment, but about complex tissue fragments in natural water.

This is why the authors speak of "natural tissue immortality." But for a general audience, it is better to understand this not literally, but as an indication of unusually long viability and ability to regenerate.

Source

Sara Jobson et al, "Natural tissue immortality: Indefinite survival of sea cucumber explants", Science Advances, 2026.