Quantcast

Giraffe

The Giraffe (Giraffa camelopardalis) is an African even-toed ungulate mammal, the tallest of all land-living animal species. There are more than 10,000 giraffes residing on national reservations in South Africa. Males can be 16 to 18 feet (4.8 to 5.5 meters) tall and weigh up to 3,000 pounds (1,360 kilograms). The record-sized bull was 19.2 feet (5.87 m) tall and weighed approximately 4,400 lbs (2,000 kg.). Females are generally slightly shorter and weigh less.

The giraffe is related to deer and cattle, but is placed in a separate family, the Giraffidae, consisting only of the giraffe and its closest relative, the okapi. Its range extends from Chad to South Africa.

Etymology and history

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. A number of European languages retain it. The Arabic word الزرافة ziraafa or zurapha, meaning “assemblage” (of animals), or just “tall”, was used in English from the sixteenth century on, often in the Italianate form giraffa.

Physical characteristics

Male giraffes are around 15″“17 feet tall at the horn tips, and weigh 1700″“4200 lb. Females are one to two feet shorter and weigh several hundred pounds less than males. Both sexes have horns, although the horns of a female are smaller. The prominent horns are formed from ossified cartilage and are called ossicones. Males sometimes develop calcium deposits which form bumps on their skull as they age, which can give the appearance of up to three further horns.

Giraffes have spots covering their entire bodies, except their underbellies, with each giraffe having a unique pattern of spots. They have long, prehensile tongues that are distinctly blue-black to protect from sunburn. Giraffes have long necks, which they use to browse the leaves of trees. They possess seven vertebrae in the neck (the usual number for a mammal). They also have slightly elongated forelegs, about 10% longer than their hind legs.

Modifications to the giraffe’s structure have evolved, particularly to the circulatory system. A giraffe’s heart, which can weigh up to 24 lb (10 kg), has to generate around double the normal blood pressure for a large mammal in order to maintain blood flow to the brain against gravity. 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 extra vascular pressure in exactly the same way as a pilot’s g-suit.

Other behavior

The giraffe browses on the twigs of trees, preferring plants of the Mimosa genus; but it appears that it can live without inconvenience on other vegetable food. A giraffe can eat 140 lb (63 kg) of leaves and twigs daily.

The pace of the giraffe is an amble, though when pursued it can run extremely fast. It cannot sustain a lengthened 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.

The giraffe defends itself against threats by kicking with great force. A single well-placed kick of an adult giraffe can shatter a lion’s skull or break its spine.

The giraffe has one of the shortest sleep requirement of any mammal, which is between 10 minutes and two hours in a 24-hour period. This has led to the myth that giraffes cannot lie down and that if they do so, they will die.

A giraffe will clean off any bugs that appear on its face with its extremely long tongue (about 18 inches/45 centimeter). The tongue is tough on account of the giraffe’s diet, which includes thorns from the tree it is making a meal of. In Southern Africa, giraffes are partial to all acacias – especially Acacia erioloba – and possess a specially adapted tongue and lips that appear to be immune to the vicious thorns.

Giraffes are thought to be mute; however, although generally quiet, they have been heard to grunt, snort and bleat and also recent research has shown evidence that the animal communicates at an infrasound level.

The instinct of some other African animals is to stay close to the giraffe, for the giraffe’s high vantage point can see predators from far away.

Evolutionary perspectives

The long neck allows a giraffe to eat from the tops of trees. However, since female giraffes are not as tall as male giraffes and tend to feed from much lower heights than their male counterparts, it is hard to say that they need the long necks purely for metabolic reasons. Furthermore, the additional length that helps a giraffe reach the top food sources makes it difficult for the same creature to drink. The ecological niche which at least male giraffes utilize is only used by a single other species, the African Elephant. It may be that the long neck originally evolved when the benefit of filling the ecological niche was more pronounced due to the presence of other, now extinct, giant ungulates in Africa.

It has been observed that males use their long necks not only for feeding, but also for combat and competition.. A female’s neck and head mass will level off after about ten years of age, while a male’s will continue to increase throughout its twenty-plus years of life.

Giraffe


comments powered by Disqus