Giraffe World

Etymology

The species name camelopardalis (camelopard) is derived from its early Roman name, where it was described as having characteristics of both a camel and a leopard. The English word camelopard first appeared in the 14th century and survived in common usage well into the 19th century. The Afrikaans language retained it. The Arabic word zurapha, meaning "assemblage" (of animals), or just "tall", was used in English from the sixteenth century on, often in the Italianate form giraffa.

Anatomy and morphology

Giraffe skeleton as illustrated by Richard Lydekker.Male giraffes are around 4.8-5.5 m (16-19 ft) tall at the horn tips, and normally weigh 1300-1700 kg (2900-3800 lb) Females are 30-60 cm (1-2 ft) shorter and weigh about 200-400 kg (400-800 lb) less than males. Giraffes have spots covering their entire bodies, except their underbellies, with each giraffe having a unique pattern of spots.

Horns
Both sexes have horns, although the horns of a female are smaller. The prominent horns are formed from ossified cartilage, and are called ossicones. The appearance of horns is a reliable method of identifying the sex of giraffes, with the females displaying tufts of hair on the top of the horns, where as males' horns tend to be bald on top - an effect of necking in combat. Males sometimes develop calcium deposits which form bumps on their skull as they age, which can give the appearance of up to three additional horns.

Neck
Giraffes have long necks which they use to browse tree leaves. They possess seven vertebrae in the neck (the usual number for a mammal) that are elongated. The vertebrae are separated by highly flexible joints. The base of the neck has spines which project upward and form a hump over the shoulders. They have anchor muscles that hold the neck upright.

Legs and pacing
Giraffes also have slightly elongated forelegs, about 10% longer than their hind legs. The pace of the giraffe is an amble, though when pursued it can run extremely fast, up to 55 km/h. It can not sustain a lengthy chase. Its leg length compels an unusual gait with the left legs moving together followed by right (similar to pacing) at low speed, and the back legs crossing outside the front at high speed. When hunting adult giraffes, lions try to knock the lanky animal off its feet and pull it down. Giraffes are difficult and dangerous prey. The giraffe defends itself with a powerful kick. A single well-placed kick from an adult giraffe can shatter a lion's skull or break its spine. Lions are the only predators which pose a serious threat to an adult giraffe.

A giraffe's heart, which can weigh up to 10 kg (22 lb) and measure about 60 cm (2 ft) long, must generate approximately double the normal blood pressure for an average large mammal to maintain blood flow to the brain. In the upper neck, a complex pressure-regulation system called the rete mirabile prevents excess blood flow to the brain when the giraffe lowers its head to drink. Conversely, the blood vessels in the lower legs are under great pressure (because of the weight of fluid pressing down on them). In other animals such pressure would force the blood out through the capillary walls; giraffes, however, have a very tight sheath of thick skin over their lower limbs which maintains high extravascular pressure in the same way as a pilot's g-suit.

Social structure and breeding habits...
Female giraffes associate in groups of a dozen or so members, occasionally including a few younger males. Younger males tend to live in "bachelor" herds, with older males often leading solitary lives. Reproduction is polygamous, with a few older males impregnating all the fertile females in a herd. Male giraffes determine female fertility by tasting the female's urine in order to detect estrus, in a multi-step process known as the Flehmen response.

Giraffes will mingle with the other herbivores in the African bush. Their company is beneficial, since they are tall enough to have a much wider scope of an area and will watch for predators.

Reproduction...
Giraffe gestation lasts between 14 and 15 months, after which a single calf is born. The mother gives birth standing up and the embryonic sack usually bursts when the baby falls to the ground. Newborn giraffes are about 1.8 m (6 ft) tall.

Mating Angolan Giraffes at Chudop waterhole, Etosha, Namibia.Within a few hours of being born, calves can run around and are indistinguishable from a week-old calf; however, for the first two weeks, they spend most of their time lying down, guarded by the mother. The young can fall prey to lions, leopards, spotted hyenas, and wild dogs. It has been speculated that their characteristic spotted pattern provides a certain degree of camouflage. Only 25 to 50% of giraffe calves reach adulthood; the life expectancy is between 20 and 25 years in the wild and 28 years in captivity (Encyclopedia of Animals).

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As noted above, males often engage in necking, which has been described as having various functions. One of these is combat. Battles can be fatal, but are more often less severe. The longer the neck, and the heavier the head at the end of the neck, the greater the force a giraffe is able to deliver in a blow. It has also been observed that males that are successful in necking have greater access to estrous females, so the length of the neck may be a product of sexual selection.[8]

After a necking duel, a giraffe can land a powerful blow with his head - occasionally knocking a male opponent to the ground. These fights rarely last more than a few minutes or end in physical harm.

Many animals when kept in captivity, such as in zoos, display abnormal behaviours. Such unnatural behaviours are known as stereotypic behaviours. In particular, giraffes show distinct patterns of stereotypic behaviours when removed from their natural environment. Due to a subconscious response to suckle milk from their mother, something which many human-reared giraffes and other captive animals do not experience, giraffes resort instead to excessive tongue use on inanimate objects.

Due to the obvious social and cultural discomfort associated with the addition of milk delivery devices, animal enclosures are often enriched with other stimuli, such as food and mental distractions (toys, scent markings etc.). This operates as a distraction, removing the giraffe's focus from its instinctual tendencies towards suckling, resulting in tongue lolling and licking of objects in close proximity.

Foraging and cleaning

Giraffes use their long, prehensile tongues to extend their reach.The giraffe browses on the twigs of trees, preferring trees of the genus Mimosa; but it appears that it can live without inconvenience on other vegetable food. A giraffe can eat 63 kg (140 lb) of leaves and twigs daily. As ruminants, they first chew their food, swallow for processing and then visibly regurgitate the semi-digested cud up their necks and back into the mouth, in order to chew again. This process is usually repeated several times for each mouthful.

Male giraffe making a cough-like mating call at the Roger Williams Park Zoo, Providence, Rhode IslandA giraffe will clean off any bugs that appear on its face with its extremely long tongue (about 45 cm/18 in). The tongue is tough due to the giraffe's diet, which can include tree thorns. In Southern Africa, giraffes feed on all acacias, especially Acacia erioloba, and possess a specially-adapted tongue and lips that are tough enough to withstand the vicious thorns of this plant.

The giraffe has one of the shortest sleep requirements of any mammal, which is between 10 minutes and two hours in a 24-hour period, averaging 1.9 hours per day.

Although generally quiet and not vocal, giraffes have been heard to make various sounds. Courting males will emit loud coughs. Females will call their young by whistling or bellowing. Calves will bleat, moo, or make mewing sounds. In addition, giraffes will grunt, snort, hiss, or make strange flute-like sounds. Recent research has shown evidence that the animal communicates at an infrasound level.