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Monkeys: Facts, Types & Pictures

Proboscis monkey
The nose of a male proboscis monkey can exceed 3.9 inches (10 centimeters), and is thought to woo females. (Image credit: © Ikki Matsuda)

Monkeys live all over the world and come in various shapes, sizes and colors. As one of our closest relatives, these mammals are very intelligent and have opposable thumbs, allowing them to use tools and play games.

There are more than 260 different types of monkeys. They are separated into two major categories: New World and Old World. The New World monkeys live in the Americas, while Old World monkeys live in Asia and Africa. One difference between the two categories is that Old World monkeys don't have prehensile tails; New World monkeys do. Old World monkeys have special pouches in their cheek where they can store food. Old World monkeys have rump pads, but New World monkeys do not. Also, Old World monkeys' nostrils are small and curved and set close together; most New World monkeys have round nostrils set far apart.

Monkeys are as varied in shape and size as humans. The world's smallest monkey is the pygmy marmoset, according to the University of Wisconsin. It weights only around 4 ounces (113 grams) and is only around 5 inches (12.7 centimeters) tall. The world's largest monkey is the mandrill. It weights around 77 pounds (35 kilograms) and is around 3 feet (1 meter) tall.

A mama gelada monkey (Theropithecus gelada) carrying her baby on her back. (Image credit: riekephotos Shutterstock)


Many people think that monkeys just eat bananas, but that isn't true. Monkeys are omnivores. This means that they eat meat and plant-based foods. Most monkeys eat nuts, fruits, seeds and flowers. Some monkeys also eat meat in the form of bird's eggs, small lizards, insects and spiders.

Habits & habitat

Most monkeys live in trees, but there are some that live in savannas or mountain areas. Monkey tribes stay on the move to find food, so one location isn't home for very long.

Monkeys are very social creatures. Groups of monkeys are called missions, tribes, troops or cartloads. A troop will work together to take care of the young monkeys in the group. They also like to play, cuddle and protect each other.

The strongest and largest of the male monkeys is the leader of the troop. In monkey genus groups that practice polygyny, the leader will mate with multiple females.

A titi monkey, part of a family of species that ranges across South America. (Image credit: Jarp2, Shutterstock)


The gestation periods for monkeys vary depending on the genus. For example, the gestation for a rhesus monkey is 164 days. Baboons have a similar gestation period of around 187 days. Chimps, on the other hand, have a much longer gestation period of around 237 days, according to the San Jose State University.

Once born, baby monkeys are primarily cared for by their mother. If the monkeys are monogamous, the baby monkey may be cared for by both parents. Many times, a young monkey will ride on its mother's back or hang from her neck. The baby is considered an adult between four and five years old.


The taxonomy of a monkey depends on what type of money it is. The higher categories are the same for all monkeys:

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: Primates

After order, the classifications become specific to the type of monkey. Here are some example classifications for two types of monkeys.

Pygmy marmoset

  • Suborder: Haplorrhini
  • Infraorder: Simiiformes
  • Family: Cebidae
  • Subfamily: Callitrichinae
  • Genus: Callithrix
  • Species: C. pygmaea

Howler monkey

  • Suborder: Haplorrhini
  • Infraorder: Simiiformes
  • Family: Atelidae
  • Subfamily: Alouattinae
  • Genus: Alouatta
  • Species: A. macconnelli (Guyanan red howler), A. belzebul (red-handed howler), A. pigra (black howler), A. caraya (black-and-gold howler), A. coibensis (Coiba Island howler), A. palliata (mantled howler), A. guariba (red-and-black howler), A. nigerrima (Amazon black howler), A. sara (Bolivian red howler), A. seniculus (red howler)

Conservation status

While many monkey species are not in danger, there are some that are very close to extinction. For example there are only 150 Tonkin Snub-Nosed monkeys in existence. Another monkey on the list is the Tana River Red Colobus. There are fewer than 1,000 of these monkeys left in the world. Both are listed on the 25 Most Endangered Primates list published by the International Union for Conservation of Nature Species Survival Commission Primate Specialist Group.

The Hainan Black-Crested Gibbon is considered one of the most critically endangered species. There are only 20 of these monkeys left in the world.

Other monkey facts

If there is a lack of food, female monkeys will stop mating until there are better circumstances for getting pregnant. Even when conditions are right, a mother will only give birth once every two years.

Proboscis monkeys only eat unripe fruit. This is because the sugars in ripe fruit ferment. The fermentation causes bloating in the stomach that can kill them.

According to NASA, the first living creature in space was a rhesus monkey named Albert I. His launch took place in White Sands, New Mexico, on June 11, 1948.

The bright blue and red colors on a mandrill's face get brighter when they are excited. They also have pouches in their cheeks where they store food for snacks.

When a troop of howler monkeys yell, they can be heard for up to three miles.

Grinning or pulling the lip is a sign of aggression in monkeys, along with yawning, head bobbing, and jerking the head and shoulders forward.

Monkeys express affection and make peace with others by grooming each other.

South American Titi monkeys are rare among primates because they mate for life. They show affection by grooming each other, intertwining their tails, holding hands, cuddling, and lip smacking.

Capuchins are skilled tool users. They can smash nuts with rocks, insert branches into crevices to capture food, and use large branches to club snakes. They are often used in lab experiments because of their intelligence.

A spider monkey is named after its long tail and lengthy spidery limbs. These monkeys can quickly walk on two legs across a tree branch.

Old World monkeys and humans share a common ancestor. Scientists say the evolutionary split may have occurred between 20 and 30 million years ago.

Nina Sen contributed to this article.

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Alina Bradford
Alina Bradford is a contributing writer for Live Science. Over the past 16 years, Alina has covered everything from Ebola to androids while writing health, science and tech articles for major publications. She has multiple health, safety and lifesaving certifications from Oklahoma State University. Alina's goal in life is to try as many experiences as possible. To date, she has been a volunteer firefighter, a dispatcher, substitute teacher, artist, janitor, children's book author, pizza maker, event coordinator and much more.