EUGENE M. MCCARTHY, PHD
pretty tall. These animals are browsers, which means they eat the leaves of bushes and, especially, trees.
To eat, a giraffe takes a branch in its mouth and tears off the leaves by pulling its head away. Like a cow, giraffes lack upper front teeth and instead have a “dental pad,” a lump of tough tissue against which the lower incisors pinch their food as they eat (see a picture of a cow's dental pad >>).
In zoos, giraffes are fed mostly on herbivore pellets, which provide them with a well balanced diet. They are also given acacia branches as a more natural type of food (What do giraffes eat in the wild? See below >>).
Typically a giraffe will eat about 30 kg (~66 lbs) of food a day (a large one may eat up to 34 kg), but can survive on as little as 15 kg. Nowak (1999, vol. 2, p. 1086) says that in giraffes the “Shoulder height is 2,500-3,700 mm [8-12 ft] and weight is 550-1,930 kg [1213-4255 lb], the average adult weigh being 800 kg [1764 lbs] (Dagg 1971).” Based on these figures, a giraffe eats about four percent of its body weight daily.
Giraffes sleep far less than most mammals and spend nearly all of their time eating (16-20 hours a day). They are ruminants and are usually chewing their cud whenever they are not eating.
The water requirements of a giraffe, which are extremely sparing, are similar to those of a camel. They can go for weeks or even months without any water at all. On average, though, a giraffe drinks about 7.5 liters (~2 gallons) of water a week.
In the wild, giraffes primarily eat the leaves and twigs of acacia, mimosa, and wild apricot trees (also various trees and shrubs in the genera Commiphora and Terminalia). Still, their diet does extend well beyond the more commonly eaten plants just mentioned. They even eat some fruit. And they also show individual food preferences.
Mostly giraffes eat plants they can easily reach. They do, however, eat some grass. But to eat short grass close to the ground, these huge animals have to either bend at the knee or splay their front legs wide apart and to the front, as in the picture at right.
Because they are browsers, giraffes eat mainly leaves and buds of shrubs and small trees that are easily in reach, although they will also eat herbs and vines, as well as fruits and flowers. They typically live on the savanna, but eat very little grass, perhaps because it doesn't suit their taste, but more likely because it's hard for them to eat anything that grows so low to the ground. Moreover, giraffes are especially vulnerable to lion predation when their heads are down while ground-feeding or drinking.
A giraffe's tough mouth and its great height allow it to reach and eat foods most other animals can't. Giraffes have a long prehensile tongue, and both the tongue and lips are virtually unaffected by thorny branches that most herbivores would not be able to utilize as food. They strip leaves from limbs, even very prickly ones, like those of the acacia (see picture above), by enclosing a portion of the branch within the mouth and pulling the head back. The impervious lips and tongue rip the leaves away.
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