Known for their distinctive red fur, orangutans are the largest arboreal mammals, spending most of their time in trees. Long, powerful arms and grasping hands and feet allow them to move through the branches. These great apes share 96.4% of our genes and are highly intelligent creatures. The name orangutan means "man of the forest" in the Malay language. In the lowland forests in which they reside, orangutans live solitary existences. They feast on wild fruits like lychees, mangosteens, and figs, and slurp water from holes in trees. They make nests in trees or vegetation to sleep at night and rest during the day. Adult male orangutans can weigh up to 200 pounds. Flanged males have prominent cheek pads called flanges and a throat sac used to make loud verbalizations called long calls. An unflanged male looks like an adult female. In a biological phenomenon unique among primates, an unflanged male can change to a flanged male for reasons that are not yet fully understood. Mothers and their young, however, share a strong bond. Infants will stay with their mothers for some six or seven years until they develop the skills to survive on their own. Female orangutans give birth only once every eight years—the longest time period of any animal. The animals are long-lived and have survived as long as 60 years in captivity. Bornean and Sumatran orangutans differ a little in appearance and behavior. While both have shaggy reddish fur, Sumatran orangutans have longer facial hair. Sumatran orangutans are reported to have closer social bonds than their Bornean cousins. Bornean orangutans are more likely to descend from the trees to move around on the ground. Both species have experienced sharp population declines. A century ago, there were probably more than 230,000 orangutans in total, but the Bornean orangutan is now estimated at about 104,700 based on updated geographic range (Endangered), and the Sumatran about 7,500 (Critically Endangered). A third species of orangutan was announced in November 2017. With no more than 800 individuals in existence, the Tapanuli orangutan is the most endangered of all great apes.