The giraffe is the tallest living animal on Earth, an unmistakable creature of the African savanna with its towering neck, long legs, and patchwork coat. A fully grown giraffe can stand five to six metres tall, high enough to peer into an upstairs window, and to browse leaves far above the reach of any other land animal.
The giraffe's most famous feature is its enormously long neck, which, remarkably, contains the same number of bones as a human neck, each one simply hugely elongated. That long neck lets the giraffe feed on the tender leaves at the tops of trees, especially acacias, that other browsers cannot reach.
The giraffe's great height demands extraordinary adaptations. It needs a powerful heart to pump blood all the way up to the brain, and special valves in the neck to prevent a dangerous rush of blood to the head when it bends down to drink. Tight skin on its lower legs works like a pressure stocking, keeping its blood from pooling in its feet.
The giraffe's neck did not appear all at once. Fossil relatives such as Samotherium had necks of intermediate length, charting the gradual stretching of the giraffe lineage over millions of years. Exactly what drove the neck to grow so long, reaching high food, winning fights, or both, is still debated by biologists.
Giraffes live in loose, shifting social groups and spend much of the day feeding, using their long, prehensile tongues, often dark in colour, to strip leaves from thorny branches. Their height gives them an excellent view of the surrounding plains, and they can spot predators such as lions from a long way off. When threatened, an adult giraffe is far from defenceless: a single kick from its powerful legs can be lethal to an attacker.
Every giraffe wears a unique pattern of patches, which helps individuals stay camouflaged among the trees and may also help them regulate their body temperature, as the skin beneath the dark patches is rich in blood vessels. Males sometimes engage in a striking contest called "necking," swinging their heavy necks and heads at one another to establish dominance.
Long taken for granted as a familiar sight, giraffes have in fact been quietly declining across much of Africa, their numbers falling as habitat is lost and fragmented and as poaching takes a toll.
Conservationists have warned of a "silent extinction" unfolding while attention focused on more obviously threatened animals. Recent research has even split the giraffe into several distinct species, some of them dangerously few in number. Efforts are now under way to protect giraffe populations and the wild savanna landscapes they help define.
