The last male northern white rhino could be about to die after becoming ill recently.
Sudan, who is old (for a rhino) at the age of 45, is kept safe under armed guard in a wildlife reserve in Kenya. He is one of only three northern white rhinos left, and the only male.
With Sudan's time on the planet significantly limited, a team of scientists are planning to push ahead with an experimental effort to use the two remaining females, Najin and Fatu, to save the entire sub-species from becoming extinct.
Wildlife photographer Ami Vitale posted on Instagram to break the news, writing: "The LAST male Northern White Rhino on the planet, named Sudan has developed a serious infection and his caregivers at Ol Pejeta Sanctuary are working hard to keep him healthy and comfortable."
She also added a quote from the sanctuary, which reads: "Even though he is now old and ailing; Sudan has been an inspirational figure for many across the world for years.
"Thousands have trooped to Ol Pejeta to see him and he has helped raise awareness for rhino conservation to millions worldwide."
Last year Tinder named Sudan 'the most eligible bachelor in the world' in an attempt to raise money for the IVF treatments that will be needed once he finally passes.
He developed the infection on his back last year and was successfully treated - however another has developed since then and is not responding well to treatment.
Elodie A. Sampere, a spokesperson for the wildlife park said: "We don't think he will last for much longer.
Sudan alongside Fatu and Najin. Credit: PA
"Euthanasia will be explored if we feel he is suffering too much and won't recover. We do not want him to suffer unnecessarily.
"Right now he is still feeding and walking around, albeit very little."
He has rallied slightly in the past few days according to his keepers, but there is little hope for a miraculous recovery.
All three of the rhinos live in the park alongside one another and are protected 24 hours a day from poachers by armed guards.
They are so valuable to poachers partly because their horn is thought be able to cure illnesses in Asia. Some experts think that it is worth more than its weight in gold.
According to charity Save the Rhino, some poachers will shoot the rhino with a tranquiliser gun before hacking the horn off. The rhino will then wake up and bleed slowly to death.
All of the sub-species of rhino in the world are currently under threat, with the western black rhino declared extinct seven years ago because of poaching.