Scientists claim to have finally discovered the secret behind how some animals can regenerate amputated limbs or damaged organs, by studying the zebrafish.
It was previously known that some species of animals used a special acid to re-grow parts of their body, but no one was sure exactly how it worked.
According to The Local, a team of researchers from the University of Konstanz in southern Germany claim they have solved the riddle after studying a master in the art of limb regeneration, the zebrafish.
While it was understood that retinoic acid played a part in the tropical freshwater fish's ability to rebuild its fins and even heart muscles, the team found it was a critical element.
"It is a huge success for us. Up to now, no-one has really looked into what the actual function of this acid is," the Daily Mail quoted Gerrit Begemann, the lead researcher as saying.
Before the fish's fins regenerate, the wound is closed with multiple layers of tissue, and the cells beneath the stump then lose their identity and form what is called blastema.
The researchers found that the fish uses a special genetic trick that allows the acid to control the formation of blastema, which means the animal is able to produce a store of cells that can rebuild the fin.
Retinoic acid is produced by animals, including humans, from vitamin A and can activate the necessary genes for regeneration.