What does it mean to be alive? A new study on an astonishing sea creature suggests the answer may be more complicated than it seems.
Some amputated fragments of Psolus fabricii — a type of sea cucumber native to the North Atlantic Ocean — puzzled researchers when they noticed that the severed parts did not simply decay and die but instead appeared to grow.
To find out more, the researchers humanely excised additional fragments from the feet, main body and tentacles of the marine animals and ran a number of lab experiments in untreated seawater. Indeed, the fragments refused to die. The various parts unexpectedly healed themselves and even managed to absorb nutrients despite lacking a mouth.
“This is the first case of tissue immortality in natural conditions,” said Sara Jobson, lead author of a study describing the finding that published Wednesday in the journal Science Advances. “These sea cucumbers are known for their high-regenerative capacity, so when they lose a tentacle or a tube foot they’re able to regrow it very well, but nobody’s ever looked at what happens to the tissues that are torn off, because we just assumed that they would die.”