Among numerous and various group of primates there are no extremely water animals, but in different time in different areas of the Earth various species of primates not connected with each other by origin had adapted to water habit of life. In Holocene such species were long-nosed monkey (Nasalis), the crab-eating macaque (Macaca fascicularis), rhesus macaque (Macaca mulatta), the Japanese macaque (Macaca fuscata) and the talapoin guenon (Miopithecus talapoin). These primates spend a significant part of time in water searching for food. They freely feel like in so alien to the majority of primates habitat: the case when the long-nosed monkey was caught in the middle of South China sea is known. Therefore it is possible to suppose, that some primates survived during Holocene-Neocaenic extinction can develop water inhabitancy or even partialllly use resources given by the sea.
The black-handed guenon is the primate adapted to semi-water habit of life. These animals spend cool winter in dry forests far from coast. But in the summer when water gets warm and at the coast there are many edible sea animals and seaweed, these monkeys go down from dry forests to the ocean and eat gifts of the sea. The monkey can swim perfectly, but this skill is not inborn - cubs study to swim at first two years of life. These species of primates is large-sized one - weight of the adult male is up to 12 kg and more, females - up to 10 kg. It is remarkable by contrast coloring of the body: the wool at adult animals is white with brownish shade, on extremities it gradually darkens: hands and feet are covered with dark-brown wool. The tail (it is longer, than body and head) also darkens to the tip, but on its end there is the snow-white hairy brush of long hair, allowing an animal to distinguish neighbours in bushes and in high grass. Cubs are entirely covered with dark wool, with age their body brightens. At adult males the face skin is bright blue, at females and cubs the face is dark. At females there are large pink sciatic calluses. Males differ by long canines, at females canines are not longer than other teeth. Nostrils of monkeys are adapted to water habit of life - they are chink-shaped and can close at the diving. Monkeys eat various kinds of forage: ground plants and roots, fruits of trees, insects. In the summer they practically completely pass to ration including sea animals and edible seaweed. They are able to apply sticks and stones to split crusts of crabs and snail shells. Black-handed guenons keep in groups of 20 - 40 individuals, including some families (the male, the female and the youngster, and also newborn). Young animals before the second year of life keep near parents, after the formation of their own pairs connection with parents strongly weakens. Cubs (usually there is only one cub, twins are rarity) are born almost at any time of year (except for an autumn - winter season), but it is more often in the beginning of spring. At the age of half-year the young animal can search for food independently, but it still long time studies at adult members of group.