While hair is usually for insulation, it may also be for sense, e.g. the vibrissae or whiskers. Horns have a bony core. Antlers are all bone without a covering of keratin, but unlike horns, are shed every year. Mammalian teeth are highly variable or heterodont . A diastema is a gap between the anterior and posterior teeth, allowing for an elongated snout, e.g., in deer.
Muscles attach at an origin and an insertion , and produce an action .
1,3 Digestive system . Will discuss more next week. Sheep and cattle are ruminants with specialized four-chamber stomachs that also function as fermentation pouches to digest the cellulose in plants. 2 Circulatory system. In a fetus, the placenta is the site of gas exchange and not the lungs.