III.

Physical Description

In addition to its great height, the giraffe is also one of the heaviest land animals. Exceptionally large males may weigh up to 1,900 kg (about 4,200 lb). Females are smaller, rarely reaching half that weight. Compared to other hoofed mammals the giraffe has a relatively short body, but its legs are disproportionately long. The front legs are marginally longer than the hind legs, a feature that contributes to the animal’s steeply sloping back. Mature giraffes have large hooves about the size of dinner plates.

Giraffes have two gaits—a loping walk and a gallop. When they walk, the animals move both feet on one side of their body in unison, followed by both feet on the other side. When they run, giraffes move the front feet together, then the back feet, swinging the hind feet up and planting them in front of the forefeet. While running, the neck of a giraffe moves backward and forward to keep the animal balanced. Giraffes have a top speed of about 56 km/h (35 mph), but because its legs are so long a galloping giraffe does not appear to be going very fast.

A giraffe’s neck can be over 1.5 m (5 ft) in length, but it contains only seven vertebrae—the same number as in most other mammals, including humans. These vertebrae are enormously elongated and are separated by very flexible joints. At the base of the neck, the thoracic vertebrae have spines that project upward, forming a hump over the shoulders. These bones anchor muscles that hold the neck upright, in the same way that cables hold up a construction crane.

The giraffe’s long neck and immense height help it eat leaves that are beyond the reach of other animals. A giraffe can extend its tongue for as much as 45 cm (18 in), wrapping it around leaves like a grasping hand, and the animal’s canine teeth have deep grooves for stripping foliage from twigs. The tongue and lips of giraffes are covered by hard growths called papillae—a vital adaptation for feeding on trees with vicious thorns. Compared to other mammals, giraffes have an unexceptional sense of smell, but their eyes are large and their vision acute. Combined with their lofty vantage point, this gives the animals a panoramic view of their surroundings.

For giraffes, bending down is an anatomical challenge. To reach ground level—for example, when drinking—a giraffe has to splay its front legs at an angle of almost 45 degrees. A giraffe’s circulatory system is also specially modified, because the high pressure needed to pump blood up to its head could cause brain damage when the head is lowered. To deal with this problem, giraffes have elastic blood vessels that relieve some of the excess pressure. They also have a series of valves in their neck veins that ensure that blood always flows from the head back toward the heart, even when this means going against gravity.

Giraffes have short, dense fur with an intricate pattern of dark patches that range from tannish-yellow to chestnut brown. This coloration helps giraffes blend in among trees and leaves, making them harder for predators to spot. Although no two giraffe skin patterns are exactly the same, some regional patterns are so common and distinct that zoologists have identified a number of giraffe subspecies based on the patterns. One of the most striking of these subspecies is the reticulated giraffe, which has large brown patches separated by thin contrasting lines, making a pattern that looks like broken paving. Another variety, the Masai giraffe, has patches with complex jagged outlines. In all giraffes, the coat color tends to become darker with age. In captivity giraffes have lived into their mid-30s, but their maximum lifespan in the wild is about 25 years.

The heads of both male and female giraffes have a pair of bony horns, permanently covered by skin and ending in a tuft of black hair. The horns of males are larger than those of females, growing up to 25 cm (about 10 in) long. The skulls of males continue to deposit layers of new bone throughout life. As a result, a male giraffe’s head becomes progressively heavier and more angular, with bony lumps that look like extra horns. This characteristic—found in no other mammal—is linked to the fights that male giraffes stage to establish dominance for mating.