There are many different types of primates. Some are very small—the smallest primate is the pygmy mouse lemur, which weighs only one ounce (30 grams). Others are very large—the largest primate is an adult male gorilla. A full-grown male gorilla can weigh 375 pounds (170 kilograms) or more, and be as tall as 6 feet (1.8 meters). Primates include the lemurs, lorises and bushbabies, tarsiers, New World monkeys, Old World monkeys, apes, and humans.
Because there are so many different types of primates, appearance varies quite a bit. Body hair may be long, as in the orangutan or the golden lion tamarin. Other primates have short fur all over the body, such as the chimpanzee or pygmy marmoset. There are many quite colorful primates. The male mandrill of Central Africa has bright red and blue on his face and red, blue, and violet coloration on his rump. The Japanese macaque is medium brown with a red face. The golden langur of China has flame orange fur with a bright blue face.
But even though primates may be quite different in size and color, they do have many things in common. Primates tend to have longer arms and legs in relation to body size than other mammals. Their hands and feet are shaped so that they can hold on to objects very well. On a primate’s foot, the big toe is set far apart from the other four digits, or toes. This allows an especially strong wraparound grasp on branches. Every primate has this special grasping action of its feet except humans. The ventral or bottom surface of both hands and feet have special pads that help primates grip. This is another way that enables primates to achieve a better hold on tree limbs. Also, primates usually have rounded skulls with a large brain for their body size. Their eyes are set forward in the face for stereoscopic vision, which allows them to see things around them in three-dimensions (or “3-D”), rather than two-dimensions, like a page in a book.
Primates are found in Africa, Asia, and South and Central America. The largest number of primates live in Africa, including the pottos, bushbabies, guenons, mangabeys, colobus monkeys, chimpanzees, gorillas, and baboons. Tarsiers, macaques, lorises, and most of the leaf monkeys live in Asia. Lemurs and aye-ayes are found only on the island of Madagascar. The New World monkeys, such as the marmosets, tamarins, and squirrel monkeys, live in South and Central America.
WHERE DO PRIMATES LIVE
Primates live in a variety of habitats, including evergreen tropical rainforests with rain throughout the year, dry scrub forests, dry areas that have forests along river banks, coastal scrublands, bamboo stands, and dry deciduous forests where trees lose their leaves each year. For example, the mandrills and chimpanzees can be found in rainforests, and the ring-tailed lemurs live in dry woodlands. Rainforests are evergreen forests with a short dry season and high rainfall. Woodlands are areas with a lot of trees and shrubs.
WHAT DO PRIMATES EAT
Primates eat a wide variety of foods. All primates may eat insects, leaves, nuts, seeds, plant gums or fluids, and fruits. But each primate may have a food preference. The indri prefers young plants and leaves, fruit, and seeds. The aye-aye eats fruit and insect larvae (LAR-vee), or young. The blue monkey eats fruits, leaves, and slow-moving insects, as well as occasional birds and small animals.
BEHAVIOR AND REPRODUCTION
Most primates are arboreal, living in trees. Some are active during the day, such as the black lemurs and chimpanzees. Others are active only at night, such as the owl monkeys and lesser bushbabies. A few primates live primarily on the ground, such as mandrill baboons and gorillas, even though they may sleep in trees for protection.
A few primates live alone most of the time, such as the orangutan and the potto. However, most primates are quite social, living together in small or large groups. Verreaux’s sifaka lives in groups of about six animals. The moustached monkey lives in groups of up to thirty-five animals. The savanna baboon may have 200 animals in its group. Depending on species, the groups have different numbers of males and females. The indri has equal numbers of males and females. The guenons, or forest monkeys, have one male to each group of adult females. This is sometimes called a harem (HARE-um) group. The gray-cheeked mangabey groups have two adult females to one adult male.
Primate females give birth to live young. Compared to other animal species of the same size, they have long pregnancies. Bushbabies are pregnant four to five months, and may have one to three babies each time. Baboons are pregnant for six months, and usually have one baby each time. Gorillas are pregnant for eight and a half months and have one baby each time. Babies are usually born covered with fur, and with their eyes and ears open.
Dedicated care by one or both parents is usual for primates. Babies nurse for a long time. There is a lot of physical contact between the infant and the mother—this is often because the infants travel with the mother, clinging to her fur. In some primate species, such as the cotton-top tamarin and Goeldi’s monkey, they travel with the father too. They may ride clinging to a parent’s front, belly, or back.
Primates often interact with each other in social ways. Grooming, or cleaning, each other is one example. Depending on species, grooming may be done with the teeth, with hands, or with a finger, or grooming claw, which has a long nail specialized for grooming. Primates also interact with sound communication. Each sound is a form of communication.
PRIMATES AND PEOPLE
People hunt some non-human primate species for meat, unproven medicinal uses of their body parts, or capture them for pets. Zoos collect primates as exhibit animals. Some primates, such as the baboon, rhesus monkey, and the common marmoset, are used in laboratory biomedical research. Current breeding programs have slowed the practice of taking these animals from the wild. A few primates, in close contact with human living areas, have become crop pests, such as the macaques who raid fruit trees that humans grow.
If not threatened, primates seldom bother human beings. However, some may harbor viruses that can be transmitted to human beings, such as Ebola, a usually fatal disease.
About one-third of all primate species are threatened. Of these, 120 species are Critically Endangered, facing an extremely high risk of extinction in the wild; Endangered, facing a very high risk of extinction; or Vulnerable, facing a high risk of extinction. Critically Endangered species include the Sumatran orangutan, one species of snub-nosed monkey, three lion tamarin species, and two gentle lemur species. Most of the problems for these tree-dwelling animals come from deforestation, or tree destruction and removal. Hunting in some areas is also a problem, as are brush fires. Tourism, while increasing local awareness, also means increased development to house and feed tourists. There are captive breeding programs and protected national parks, but as habitat loss continues, extinction of several species is predicted.