Tissues detached from sea cucumbers found to remain alive for years

Observations made on a species of sea cucumber living in the North Atlantic have revealed that some detached tissues do not merely show short-term signs of life, but can survive for years. According to a report by Euronews, the discovery has sparked a new debate regarding biological definitions of where life begins and ends.

In a study conducted at the Ocean Sciences Centre of Memorial University in Canada, the cold-water species Psolus fabricii was examined. Researchers noticed that a few small tube feet detached while removing the sea cucumber from an aquarium. While such detachment can occur in sea cucumbers, what surprised the research team was that these fragments did not die quickly.

Initial observations determined that the tissues remained alive for weeks without showing signs of decay. Consequently, the team subjected the detached tissue fragments to more detailed examination. Ultimately, it was observed that these small tissue pieces survived for over three years.

Researchers found that not only the tube feet but also the tentacles around the mouth could remain alive in a similar fashion. Examinations showed that the detached tissues continued to repair themselves, maintained immune functions, and kept their neural networks operational.

One of the striking questions of the study was how these tissues obtained energy without a mouth or digestive system. According to the research team, the tissue fragments are able to stay alive by absorbing nutrients directly through their cell membranes.

THEY RESPONDED TO ENVIRONMENTAL STIMULI

It was also observed that the detached tissues did not remain alive in a merely passive manner. Researchers determined that when they moved the water or touched the tissues lightly, these fragments would contract and withdraw just like a normal sea cucumber. This behavior indicates that the neural networks are capable of responding to environmental stimuli.

The study's lead author, Sara Jobson, distinguished the finding from typical examples of regeneration in a statement to Popular Science. Jobson said, “When a lizard loses its tail, the tail may grow back, but we don't see the detached tail continuing to live on its own. What we see here is not like that. We compare it to the independently moving ‘Thing’ character from The Addams Family.”

Researchers emphasize that these tissues have a significant deficiency: they cannot reproduce. Therefore, it is difficult to consider them as fully new organisms. However, the fact that they do not die, heal, and respond to the environment places them on the edge of definitions of life.

Jobson and her team jokingly call these tissue fragments “lab zombies” in the laboratory. Jobson stated that although they maintain many fundamental processes associated with life, they cannot pass on their genetic information to subsequent generations, which she noted adds a philosophical dimension to the subject.

While it is noted that the findings could strengthen the debate over a “third biological state” between life and death, not everyone in the scientific world shares the same view. José García Arrarás, a regenerative biology expert at the University of Puerto Rico, finds the discovery exciting but believes that a piece of tissue that cannot reproduce cannot be considered an independent organism.