The oldest-known land animal in the world is an Aldabra giant tortoise named Jonathan. He is believed to be 194 years old.
Scientists have a couple of ideas about why he has lived for so long. They think he has special genes and can keep important systems in his cells working as they do in younger animals.
Members of this species are known to live more than 100 years. But Jonathan has lived much longer than that. Scientists have studied Jonathan to explore the secrets of his long life.
They found 287 genes with types special to Jonathan. Some are linked to repairing DNA and stopping tumours. The tortoise also has extra copies of a gene that creates a protein that hunts down ageing and cancerous cells.
