Pan Pan the panda, the world's oldest male panda, died of cancer Wednesday at age 31, which researchers say is the equivalent of 100 in human years.
While staff at the research center in Sichuan where Pan Pan lived say his death is "heart breaking," they're thankful for his help repopulating the captive panda population.
Pan Pan was the father to over 130 panda cubs, more than a quarter of the 422 pandas living in captivity today, and helped remove pandas from the endangered species list.
Pan Pan, whose name means "hope" or "expectation," lived a long and full life. A giant panda's average lifespan is 20 years. While Pan Pan suffered from bad eyesight, his keepers say he managed to find his way around by smell and touch.
His many children live in zoos as far away as California and Brussels. Most pandas born in zoos have trouble mating, but Pan Pan lived his early years as a wild panda.
In a social media post from November, China's panda Protection and Research Center said that Pan Pan "brought hope" to the center with his "energy and vitality." Earlier this year, the World Wide Fund for Nature announced that pandas were no longer endangered thanks to conservation efforts.
Pan Pan and another panda, An An, as cubs
In a farewell post on Wednesday the center wished that Pan Pan "doesn't suffer pain in heaven. May 'Grand Pan' rest in peace."