form an udder in the groin region. Secretory glands in the skin are present in virtually all species and can be located in different places, such as in the eyes, behind the horns, the neck, or back, on the feet, or in the anal region. Lifestyle Distribution and habitat Artiodactyls are native to almost all parts of the world, with the exception of Oceania and Antarctica. Humans have introduced different artiodactyls worldwide as hunting animals. Artiodactyls inhabit almost every habitat, from tropical rainforests and steppes to deserts and high mountain regions. The greatest biodiversity prevails in open habitats such as grasslands and open forests. Social behavior The social behavior of even-toed ungulates varies from species to species. Generally, there is a tendency to merge into larger groups, but some live alone or in pairs. Species living in groups often have a hierarchy, both among males and females. Some species also live in harem groups, with one male, several females, and their common offspring. In other species, the females and juveniles stay together, while males are solitary or live in bachelor groups and seek out females only during mating season. Many artiodactyls are territorial and mark their territory, for example, with glandular secretions or urine. In addition to year-round sedentary species, there are animals that migrate seasonally. There are diurnal, crepuscular, and nocturnal artiodactyls. Some species' pattern of wakefulness varies with season or habitat. Reproduction and life expectancy Generally, even-toed ungulates tend to have long gestation periods, smaller litter sizes, and more highly developed newborns. As with many other mammals, species in temperate or polar regions have a fixed mating season, while those in tropical areas breed year-round. They carry out polygynous mating behavior, meaning a male mates with several females and suppresses all competition. The length of the gestation period varies from four to five months for porcine, deer, and musk deer; six to ten months for hippos, deer, and bovines; ten to thirteen months with camels; and fourteen to fifteen months with giraffes. Most deliver one or two babies, but some pigs can deliver up to ten. The newborns are precocial (born relatively mature) and come with open eyes and are hairy (with the exception of the hairless hippos). Juvenile deer and pigs have striped or spotted coats; the pattern disappears as they grow older. The juveniles of some species spend their first weeks with their mother in a