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
Polychaete group includes predators, herbivores, filter feeders, scavengers, and parasites. In general, however, they possess a pair of jaws and a pharynx that can be rapidly everted, allowing the worms to grab food and pull it into their mouths. In some species, the pharynx is modified into a lengthy proboscis. The digestive tract is a simple tube, usually with a stomach part way along. The smallest species, and those adapted to burrowing, lack gills, breathing only through their body surfaces. Most other species have external gills, often associated with the parapodia. A simple but well-developed circulatory system is usually present. The