Crab monkeys are often used for experiments because they are abundant, easy to breed, and have a short reproductive time. Plus, they are physiologically close to humans, so if they are used for experiments, they can also save money. Crab-eating monkeys and rhesus monkeys are widely used as laboratory animals in medical experiments.

Crab-eating monkeys, also known as long-tailed macaques, have an adult body length of about 40-47 centimeters and a tail length of 50-60 centimeters. It is a herd animal, often tens or hundreds of them live together.

Crab-eating monkeys like to drink water and like to go to the sea after low tide to forage for crabs and shellfish, hence the name crab-eating macaque. In addition to crabs, fruits, leaves, small animals and birds are all objects of their consumption. With the deterioration of the living environment, scientists have even discovered that some crab-eating macaques have learned to hunt fish to expand their food source. Crab-eating macaques like to inhabit tropical rainforests, primary forests, secondary forests, as well as coconut groves near rivers and mangrove forests along the coast, mainly in some countries and regions in Southeast Asia.