Chlorocebus

The genus *Chlorocebus* consists of medium-sized primates known as Old World monkeys. Scientists currently recognize six distinct species within this group. Some researchers classify these species as a single species with many subspecies. The names "vervet monkey" and "green monkey" are often used for the whole genus. However, these names also refer specifically to *Chlorocebus pygerythrus* and *Chlorocebus sabaeus*. These monkeys are native to sub-Saharan Africa, ranging from Senegal and Ethiopia to South Africa.

Physically, these monkeys show clear differences between males and females, a trait called sexual dimorphism. Their fur color on their backs varies from pale yellow to dark brown. Their faces, hands, and feet are black and hairless. Males weigh between 5 and 9 kilograms, while females weigh between 3 and 6 kilograms. Adult males also have a tail measuring 35 to 45 centimeters. Males possess a striking light-blue scrotum, which is most visible during the mating season.

*Chlorocebus* monkeys have a unique way of living in their environment. They are semi-arboreal and semi-terrestrial. This means they spend much of their day on the ground but sleep in trees at night. Because they must drink water daily, they stay near lakes or rivers. They are diurnal, meaning they are active during the day. They are most active in the early morning and late afternoon. Like other Old World monkeys, they use cheek pouches to store food.

Social life for these primates is highly complex and organized. They live in groups containing multiple males and multiple females. These groups can grow as large as 76 individuals. The group follows a strict hierarchy where dominant members get priority for food. They also practice female philopatry. This is a social system where females stay in their birth range. In contrast, males leave the group once they reach sexual maturity.

Communication is vital for maintaining these social structures and staying safe. These monkeys use many different vocalizations to share information. They have specific alarm calls to warn the troop about different predators. They also use calls to warn other groups to stay away from their territory. Facial expressions and body posturing are also used to communicate. Within the group, monkeys use physical affection to bond family members. They may even use deception to gain benefits within their social alliances.

These primates are among the most omnivorous primates in existence. Their diet includes leaves, seeds, nuts, fruit, and flowers. They also eat invertebrates, bird eggs, and small vertebrates like lizards or rodents. Their food choices change with the seasons to match what is available. In the Caribbean, where they have become naturalized, they may even take food from tourists. On the island of Saint Kitts, they are known to take alcoholic drinks left on beaches.

History has moved these monkeys far from their African origins. In past centuries, settlers and traders transported them to the Caribbean. Many escaped or were released, forming new colonies on islands like Barbados and Saint Kitts. Today, they are found in places like Anguilla, Saint Martin, and even Florida. However, they face challenges in many areas. In Africa, populations in urban areas are declining due to habitat loss and urbanization. They also face threats from vehicles, predators, and hunting.

*Chlorocebus* monkeys play a massive role in modern medical science. Since the 1950s, they have been used to help produce vaccines for smallpox and polio. They are excellent models for studying high blood pressure because they develop it naturally. They are also essential for studying AIDS. These monkeys carry the simian immunodeficiency virus, or SIV. SIV is related to the human virus known as HIV. Because the monkeys do not get sick from SIV, scientists study them to understand how the body can protect itself.