A piece of sea cucumber tissue cut from its body can survive alone in open seawater for years, crawling along the seafloor as if nothing happened.
Researchers in Norway discovered that severed tube feet and body wall fragments from the cold-water sea cucumber species Parastichopus tremulus remained alive and mobile for up to 24 months in laboratory tanks. Some tissue samples even showed signs of cell division years after being detached.
A body part that refuses to die
The study, led by scientists at the University of Oslo and the Institute of Marine Research in Norway, began as a routine observation. While keeping sea cucumbers in tanks for other experiments, researchers noticed that small pieces of tissue that had broken off were still moving days later. Curious, they decided to test how long the fragments could persist.
They collected tissue samples from sea cucumbers caught in the cold, deep waters off the Norwegian coast. In the lab, the severed pieces were kept in natural seawater without any special nutrients or care. The fragments continued to crawl using their tube feet, the same tiny appendages the whole animal uses to move along the ocean floor.
Why local scientists and fishermen took notice
For Norwegian marine biologists, this finding challenges basic assumptions about what it means for an animal to be alive. Sea cucumbers are common in the cold waters of the North Atlantic, and local fishermen often pull up damaged specimens in their trawls. The study suggests that even badly injured sea cucumbers might shed living tissue that persists long after the original animal is gone.
The researchers used fluorescent dyes to track cell activity in the fragments. They found that cells in the severed tissue continued to divide, a sign of active life. The tissue did not grow into a new sea cucumber, but it did not decay either. It simply kept moving.
What this means for understanding survival
The discovery opens questions about how other marine animals might shed and sustain living tissue in the wild. Sea cucumbers are known for their ability to regenerate lost body parts, but the idea that a detached fragment can remain independently mobile for years had not been documented before.
The study was published in the Journal of Experimental Biology. The authors noted that the tissue fragments did not feed or grow, but they did respond to touch and light, suggesting a basic level of sensory awareness. For now, the researchers say they do not know the upper limit of how long the tissue can survive.
