The giraffe is one of the quintessential large African mammals. It is one of those creatures that many people travel right across the world hoping to see. It is a completely unique animal that is synonymous with the African savannas.
The name ‘giraffe’ supposedly comes from the Arabic word ‘zarafah’, which means to ‘walk swiftly’. The species name camelopardalis is derived from ancient Greek and refers to a combination of camel and leopard (i.e. a camel with leopard-like spots).
Due to their strange shape, with long legs, necks and faces, giraffes cannot really be mistaken for any other animal. They are the tallest land mammals, reaching a maximum height of over 5 metres and a shoulder height of up to 3.5 metres. They are able to feed on plant matter that almost no other animals can get to and thus fill their own niche, with very little competition from other herbivores.
Giraffes are browsers and particularly like to feed on Acacia (now Vachellia or Senegalia) trees, as well as Combretums and Terminalias. Since Acacia trees in Africa generally have thorns, the tongue of the giraffe has been purposefully adapted to deal with this. A giraffe’s purple-coloured tongue is exceptionally long (over 40 cm) and highly manoeuvrable. It also has a hard surface, covered with papillae and the saliva is thick and sticky. The upper palate is hard, in order to deal with the thorns.
Giraffes fall under the Order Ruminantia and have a four-chambered stomach. They chew the cud, like cattle and antelope, and it is amazing to watch them as they fill their mouths up with leaf matter until their cheeks are bulging. They then chew the plant matter and one can see the food (in the form of a lump) going all the way down the long throat and neck towards the stomach. A few seconds later a bulge travels all the way up the neck and the cheeks puff out again as some of the less-processed plant matter is regurgitated back into the mouth for re-chewing.
The family Giraffidae is comprised of two species, namely the giraffe and the okapi (Okapia johnstoni). The okapi is a smaller, darker, antelope-like giraffe with a dark chocolate-brown coat and white zebra-like stripes on the legs and rump. Their necks are not as long as those of giraffes and they are found in the dense jungles of the Democratic Republic of Congo and Uganda. They are exceptionally rare to see.
There are three main groupings of true giraffes i.e. those that occur in central-western Africa, those that occur near the Horn of Africa and those that occur from the equator south to South Africa. There are nine sub-species of giraffes, namely:
the West-African giraffe (subsp. peralta)
the Kardofan giraffe (subsp. antiquorum)
the Nubian giraffe (subsp. camelopardalis)
the reticulated giraffe (subsp. reticulata)
the Rothschild’s giraffe (subsp. rothschildi)
the Masai giraffe (subsp. tippelskirchi)
the Cape / southern giraffe (subsp. giraffa)
the Angolan giraffe (subsp. angolensis)
the Luangwa / Thornicroft’s giraffe (subsp. thornicrofti)
The only subspecies that occurs in South Africa is the southern giraffe. The subspecies differ mainly in slight changes to the lattice patterning on the body. In the southern giraffe the older males often get darker and darker with age and some of the big bulls in our area have almost black patches interspersed with paler bands.
The main differences between male and female giraffes are in the size (males can get much taller and heavier – up to 1 400 kg, as opposed to 950 kg for females) and the shape of the horns (also known as ossicles). The horns of females are slightly thinner and are tufted on top, whereas the horns of the males get thicker and go bald on top. Giraffes are born with horns. Initially they are not attached to the skull and are composed of cartilage. They are neatly folded back on the head and only straighten out and calcify as the young giraffe grows. Male giraffes often get up to three other horns or bony lumps on their face. These include a large bump on the forehead and two smaller bumps behind the head.
Male giraffes use the horns when fighting and establishing a hierarchy amongst each other. Older bulls generally have much heavier heads and stronger horns than younger ones. When sparring the males tend to stand side to side and swing their heads at each other like battering rams. They are able to knock their opponent down with a good blow and can in fact kill the other with a well-timed accurate hit, particularly if one knocks the other to the ground, as a hard fall may break the neck of a giraffe.
Giraffes do not have a set social structure and are considered to be non-territorial. One can see giraffes either alone or in groups. These herds / journeys / towers may consist of only one sex or both together.
It is believed that giraffes evolved their long necks for various reasons. These include to eliminate competition for food from other browsers, to give them better visibility of potential predators and to get better power and leverage when fighting. This evolutionary growth of the long neck and long legs have meant that the entire body of the giraffe has had to adapt in order to function properly. The cervical vertebrae are much longer and thicker than most other animals (although there are still only seven neck vertebrae, as with most other mammals).
The circulatory system of the giraffe has several adaptations for its great height. Its heart is very large and can weigh more than 11 kg. As the blood must travel a long way from the heart to the head a giraffe’s blood pressure is approximately double that required by humans. Giraffes, furthermore, have unusually high heart rates for their size, at 150 beats per minute.
When the animal lowers its head the blood rushes down fairly unopposed and a rete mirabile (a complex system of arteries and veins lying very close to each other) in the upper neck prevents excess blood flow to the brain. When it raises again, the blood vessels constrict and direct the blood into the brain so the animal doesn’t faint.
Another problem that the giraffe faces, as a result of its long neck, is that it is very difficult to lower its head down to water to drink. In order to accomplish this a giraffe needs to spread its front legs wide open. They are very vulnerable when drinking, as they tend to rely on their eyesight to spot predators, and when their heads are down they cannot see very far around them.
Because of their strange shape giraffes are unable to reach many areas of their bodies for grooming purposes and therefore are often infested with parasites such as ticks (particularly on the belly and under the tail) and are therefore quite reliant on oxpecker birds to help get rid of these pests.
The growth of the long neck in giraffes has also affected the sounds that a giraffe makes. They are generally considered to be silent animals although they do sometimes make noises such as coughing and bleating noises. At night it is rumoured that giraffes appear to hum to each other above the infrasound range. The reason for this is still unclear.
Giraffes tend to have only two forms of locomotion / gaits i.e. walking and galloping. While walking giraffes move both legs on the left hand side at the same time, followed by the movement of both right-hand legs. The long neck sways from side to side in order to counter-balance the giraffe. This particular style of walking is known as parallel walking (as opposed to cross-waking, which is the style that most antelope use, where the left front foot moves at the same time as the right back foot and vice versa). When galloping giraffes are able to attain speeds up to 60 kilometres per hour.
Giraffes do occasionally sit down with their legs tucked under their bodies. They tend to sleep in this position, although they are able to sleep standing up. They are, however, very vulnerable when sitting down (it takes a while to stand up from that position), and therefore do not sit down for long periods of time and usually only when there are other giraffes in the nearby vicinity. It is estimated that giraffes only sleep intermittently for a total of 4-5 hours per day / night.
The life-span of a giraffe is generally in the region of 25 years, although a particular giraffe that was kept in a zoo managed to attain an age of 36 years.
Males giraffes test the sexual readiness of females by tasting the hormones in their urine. Once an oestrous female is detected, the male will attempt to court her. When courting older, larger males will keep younger ones at bay. A courting male may lick a female’s tail, rest his head and neck on her body or nudge her with his horns. During copulation, the male stands on his hind legs with his head held up and his front legs resting on the female’s sides. This is quite a difficult position to maintain and there are many false starts before the male gets it right. Mating is very brief.
The gestation (pregnancy) period of a giraffe is approximately 15 months and a single calf is usually born. Females give birth to their calves while standing. The calf then falls quite a distance to the ground (a rather rude awakening to the world). The young calf grows very quickly and within the first year it may even may double its height. Within a few hours of birth, the calf can run around. For the first 1–3 weeks, it spends most of its time hiding, where after it may join up in a nursery herd. They are generally weaned within a year. Females reach sexual maturity at the age of four years whereas males will generally only get to mate after seven years when they are better able to compete with other males.
The main predators of giraffes are lions and humans, although it has been recorded that crocodiles may also kill them on occasion.
Giraffes are categorized by the IUCN as animals of ‘least concern’ and it is estimated that there are at least 80 000 giraffes living in the wild. The West-African giraffe and the Rothschild giraffes are both considered to be endangered and there are only a few hundred individuals of each of these sub-species left. It is very likely that these sub-species, as well as the Nubian giraffe and the Kardofan giraffe may go extinct in the near future.
Just another interesting tit-bit of information about the giraffe is that one of the constellations of stars in the sky, described and named in the seventeenth century, is known as Camelopardalis and supposedly depicts a giraffe.