Crab-eating macaque findings. One of the most well known examples of experiments on crab-eating macaques is the 1981 Silver Spring monkeys case. In 2014, 21,768 crab-eating macaques were imported in the United States to be used in experimentation. The crab-eating macaque has the third-largest range of any primate species, behind only humans and rhesus macaques. The IUCN Red List categorizes the species as Least Concern, and CITES lists them as Appendix II ("not necessarily threatened with extinction", in which trade must be controlled to avoid use incompatible with their survival). A recent review of their populations suggests a need for better monitoring
Coprophagia so to allow tough plant materials to be digested more efficiently by passing twice through the digestive tract. Other species may do so only under unusual conditions. Coprophagia has been observed in some people with schizophrenia and pica. Coprophagous insects consume and redigest the feces of large animals. These feces contain substantial amounts of semi-digested food, particularly in the case of herbivores, owing to the inefficiency of the large animals' digestive systems. Two feces-eating insects are certain species of fly and the dung beetle. In regards to the dung beetle, their diet is mainly in the form of the microorganism-rich