(CNN) The South Atlantic island of St. Helena is celebrating the birthday of the world's oldest living land animal -- a Seychelles giant tortoise called Jonathan, who is turning 190.
The island governor's house, where Jonathan has spent most of his life, is marking the occasion by opening up for three days to visitors wishing to celebrate the "historic milestone."
Officials on the island -- a British overseas territory -- have also made a series of commemorative stamps.
While there's no real record of his birth, Jonathan is thought to have been born around 1832.
He was brought to St. Helena from the Seychelles in 1882 as a gift to Sir William Grey-Wilson -- who later became governor.
But Jonathan could actually be as old as 200, according to Matt Joshua, head of tourism on St. Helena.
According to Guinness World Records, Jonathan is also the oldest ever chelonian, a category that encompasses all turtles, terrapins and tortoises.
The previous oldest chelonian was Tu'i Malila, a radiated tortoise that lived to be at least 188. Presented to the royal family of Tonga by British explorer Captain James Cook in around 1777, Tu'i Malila died in 1965.
In St. Helena, Jonathan is something of a celebrity. The elderly animal lives alongside three other giant tortoises -- David, Emma and Fred.
Though old age has left Jonathan blind and with no sense of smell, his hearing is excellent. According to Guiness World Records, he responds well to the sound of his vet's voice.
Despite some of his senses now failing, Jonathan's vet, Joe Hollins, told Guinness World Records that the animal still has plenty of energy -- though this varies with the weather.
"On mild days, he will sunbathe -- his long neck and legs stretched fully out of his shell to absorb heat and transfer it to his core," Hollins said.
In colder weather, he prefers to "dig himself into leaf mold or grass clippings and remain there all day."
Hollins added: "In spite of his age, Jonathan still has a good libido and is seen frequently to mate with Emma and sometimes Fred -- animals are often not particularly gender-sensitive!"