Antelope - Morphology

Morphology

All bovids have even-toed hooves, horizontal pupils, ruminating guts, and (in at least the males) bony horns. These basic characteristics, however, mask huge differences in appearance between antelopes, cattle, goats, and sheep, and among the antelopes themselves. For example, a male common eland can measure 178 cm (70 in) at the shoulder and weigh almost 950 kg (2,100 lb), whereas an adult royal antelope may stand only 24 cm (9.4 in) at the shoulder and weigh a mere 1.5 kg (3.3 lb).

Not surprisingly for animals with long, slender yet powerful legs, many antelopes have long strides and can run fast. Some (e.g. klipspringer) are also adapted to inhabiting rock koppies and crags. Both dibatags and gerenuks habitually stand on their two hind legs to reach acacia and other tree foliage. Different antelope have different body types, which can affect movement. Duikers are short, bush-dwelling antelope that can pick through dense foliage and dive into the shadows rapidly. Gazelles and springbok are known for their speed and leaping abilities. Even larger antelope, such as nilgai, elands, and kudus, are capable of jumping 8 ft (2.4 m) or greater, although their running speed is restricted by their greater mass.

Antelopes have a wide variety of coverings, through most have a dense coat of short fur. In most species, the coat (pelage) is some variation of a brown colour (or several shades of brown), often with white or pale under-bodies. Exceptions include the zebra-marked zebra duiker, the grey, black, and white Jentink's duiker; and the black lechwe. Most of the "spiral-horned" antelopes have pale, vertical stripes on their backs. Many desert and semidesert species are particularly pale, some almost silvery or whitish (e.g. Arabian oryx); the Beisa and southern oryxes have gray and black pelages with vivid black-and-white faces. Common features of various gazelles are white rumps, which flash a warning to others when they run from danger, and dark stripes mid-body (the latter feature is also shared by the springbok and beira). The springbok also has a pouch of white, brushlike hairs running along its back, which opens up when the animal senses danger, causing the dorsal hairs to stand on end.

Antelopes are ruminants, so have well-developed molar teeth, which grind cud (food balls stored in the stomach) into a pulp for further digestion. They have no upper incisors, but rather a hard upper gum pad, against which their lower incisors bite to tear grass stems and leaves.

Like many other herbivores, antelopes rely on keen senses to avoid predators. Their eyes are placed on the sides of their heads, giving them a broad radius of vision with minimal binocular vision. Their horizontally elongated pupils also help in this respect. Acute senses of smell and hearing give antelopes the ability to perceive danger at night out in the open (when predators are often on the prowl). These same senses play an important role in contact between individuals of the same species; markings on their heads, ears, legs, and rumps are used in such communication. Many species "flash" such markings, as well as their tails; vocal communications include loud barks, whistles, "moos" and trumpeting; many species also use scent marking to define their territories or simply to maintain contact with their relatives and neighbors.

Many antelope are sexually dimorphic. In most species, both sexes have horns, but those of males tend to be larger. Males tend to be larger than the females; however, exceptions in which the females tend to be heavier than the males include the bush duiker, dwarf antelope, Cape grysbok, and oribi, all rather small species. A number of species have hornless females (e.g. sitatunga, red lechwe, and suni). In some species, the males and females have differently coloured pelages (e.g. blackbuck and nyala).

The size and shape of antelope horns varies immensely. Those of the duikers and dwarf antelopes tend to be simple "spikes", but differ in the angle to the head from backward curved and backward pointing (e.g. yellow-backed duiker) to straight and upright (e.g. steenbok). Other groups have twisted (e.g. common eland), spiral (e.g. greater kudu), "recurved" (e.g. the reedbucks), lyrate (e.g. impala), or long, curved (e.g. the oryxes) horns. Horns are not shed and their bony cores are covered with a thick, persistent sheath of horny material, both of which distinguish them from antlers.

Horns are efficient weapons and tend to be better developed in those species where males fight over females (large herd antelope) than in solitary or lekking species. With male-male competition for mates, horns are clashed in combat. Males more commonly use their horns against each other than against another species. The boss of the horns is typically arranged in such a way that two antelope striking at each other's horns cannot crack each other's skulls, making a fight via horn more ritualized than dangerous. Many species have ridges in their horns for at least two-thirds the length of their horns, but these ridges are not a direct indicator of age.