The word “monkey” describes 264 distinct species, each with unique characteristics, including size and weight. Since so many different monkeys exist, there is no single average or usual monkey weight. They can roughly be described as small, or under 15 pounds; medium, or between about 15 and 30 pounds; and large, or 30 pounds and over.
New World monkeys live primarily in tropical South America, especially the Amazon rainforests; the range of a few species extends northward as far as southern Mexico or southward into northern Argentina. Among the smaller New World forms that have endeared themselves to humans with their antics and their tamability are the alert marmosets, often tufted and colourfully arrayed, and the inquisitive squirrel, woolly, and capuchin monkeys—all of which exhibit in marked degree the curiosity and cleverness ascribed to monkeys generally. Larger New World species include the acrobatic spider monkeys and the noisy howlers. Other New World monkeys include uakaris, sakis, and titis.
Monkeys comprise a wide range of species throughout much of the tropical world. Despite their raw variety, most of them face threats from human development, capture and hunting. Though all monkeys have many similar characteristics and a close relationship to humans, an early evolutionary shift created two major groups today: “old” and “new” world monkeys. Though they don’t walk on two legs, monkeys are closely related to humans–only great apes, such as chimpanzees, are more related. Monkeys are some of the most popular animals in the world.
Monkey Appearance And Behavior
Monkeys are something of a cousin to apes. Great apes-including chimpanzees, gorillas and orangutans–have larger brains and no tails. There exist over 250 species of monkeys, including macaques, tamarinds, and marmosets. Monkeys come in a wide range of sizes, colors and behaviors. These range from the pygmy marmoset, which less than six inches tall and weighs about as much as a deck of playing cards, to the colorful-nosed mandrill, which can weigh over 100 pounds and top out at over three feet long.
Overall, monkeys fall into two broad categories of appearance. Old world monkeys, or simiiformes catarrhini, mostly have more forward-facing noses, similar to humans. Virtually all catarrhini have tails, though none of them are prehensile, meaning they cannot use them to grab objects such as tree branches. The baboon is one example of an old world group of monkeys, with long snouts and gray, brown or tan fur that gets long around the chest and head. The tail of the baboon is approximately five inches long.
Simiiformes platyrrhini, meanwhile, have flatter noses with nostrils that face more to the sides. They are also the only types of monkeys that feature prehensile tails, meaning they can use their tails to grab objects and hang from trees. One common example of a platyrrhini is the spider monkey, which has pink face poking out of noticeably long black fur.
The largest monkey is the mandrill, or Mandrill sphinx, which averages around 77 pounds and 3 feet tall, but a few can reach over 100 pounds. Mandrills are an Old World monkey and are found in equatorial Africa, where they make their home in rain forests. They are easily identified and well known for their brilliant facial markings, which include blue and red stripes on the skin around their noses.
Old World Monkeys
Old World monkeys, which include 133 species, are those found in Africa and Asia. They make up the Cercopithecidae family, and are generally medium to large in size, ranging from 3.5 to 110 pounds. Well-known Old World monkeys include the baboon, which weighs between 33 and 82 pounds; the rhesus monkey, which weighs around 17 pounds; and several species of langurs, which weigh, on average, between 20 and 30 pounds.
New World Monkeys
New World monkeys, or families Cebidae and Callitricidae, are found in South America, and include 53 known species. They are generally smaller than Old World monkeys, ranging between a quarter of a pound and 33 pounds. Most New World monkeys are not equipped to live on the ground, and spend the majority of their time in the rain forest canopy. Well-known New World monkeys include marmosets and tamarins, which range from a quarter of a pound to 2 pounds; the capuchin monkey, which weighs between 3 and 9 pounds; and the howler monkey, which weighs between 15 and 22 pounds.
Popular Pet Monkeys
Monkey species commonly kept as pets are usually small and medium-size, ranging from a quarter of a pound for the pygmy marmoset to 35 pounds for the Celebes or Java macaques. Among the most popular pet monkeys are the vervet at 4 to 15 pounds, common and silvery marmosets at three quarters of a pound to 1 pound, the squirrel monkey at around 2 pounds, and the spider monkey at 13 to 25 pounds.
Top Monkey Facts
- Monkeys at risk: out of over 250 species, only one type of monkey was listed as being of “least concern” for extinction!
- Born tree: some monkeys can swing through branches as fast as a racehorse!
- Hanging out: Unlike their cousins, the apes, monkeys often have long tails–but only new world monkeys can use them to hang!
- Pocket-sized: the world’s smallest monkey, the pygmy marmoset, is less than six inches long and weighs less than a pack of playing cards!
- Mega-sized: the world’s largest monkeys can reach significant sizes. For example, male mandrills have reached 119 pounds in size!
- While the thought of a pet monkey may seem nice, they are illegal to own in most states.
Are Monkeys Dangerous?
Monkeys can be dangerous as pets, transmitting disease and giving nasty bites, but the risk is relatively small. From 1990 to 2013, the Humane Society had documented 275 attacks from “captive primates” in the U.S., none of which caused death. The majority of monkeys in the wild are shy, preferring to hide from humans rather than confront them.
Can You Have A Monkey As A Pet?
Caring for a monkey is complicated, and a number of states in the U.S. and other countries prohibit or limit who can own a monkey. For example, Alabama allows monkeys as pets; New Hampshire bans monkeys as pets; and Idaho allows monkey ownership, provided you have a special permit.
Are Chimpanzees Monkeys?
Chimpanzees are actually part of a separate classification of primates, called “great apes.” Great apes are a small group of primates that share many features with monkeys, but are larger, smarter and tail-less. Great apes also share a closer genetic connection to humans. The chimpanzees, particularly, are humans’ closest genetic relative, sharing 99 percent of our genetic code!
Are Monkeys Herbivores, Carnivores, Or Omnivores?
Monkeys are Omnivores, meaning they eat both plants and other animals.