Legs, Locomotion and Posture
The front and back legs of a giraffe are approximately the same length. The radius and ulna of the front legs are articulated by the carpus, which, while structurally equivalent to the human wrist, functions as a knee. The foot of the giraffe reaches a diameter of 30 cm (12 in), and the hoof is 15 cm (5.9 in) high in males and 10 cm (3.9 in) in females. The rear of each hoof is low and the fetlock is close to the ground, allowing the foot to support the animal's weight. Giraffes lack dewclaws and interdigital glands. The giraffe's pelvis, though relatively short, has an ilium that is outspread at the upper ends.
A giraffe has only two gaits: walking and galloping. Walking is done by moving the legs on one side of the body at the same time, then doing the same on the other side. When galloping, the hind legs move around the front legs before the latter move forward, and the tail will curl up. The animal relies on the forward and backward motions of its head and neck to maintain balance and the counter momentum while galloping. The giraffe can reach a sprint speed of up to 60 km/h (37 mph), and can sustain 50 km/h (31 mph) for several kilometers.
A giraffe rests by lying with its body on top of its folded legs. To lie down, the animal kneels on its front legs and then lowers the rest of its body. To get back up, it first gets on its knees and spreads its hind legs to raise its hindquarters. It then straightens its front legs. With each step, the animal swings its head. The giraffe sleeps intermittently around 4.6 hours per day, mostly at night. It usually sleeps lying down, however, standing sleeps have been recorded, particularly in older individuals. Intermittent short "deep sleep" phases while lying are characterized by the giraffe bending its neck backwards and resting its head on the hip or thigh, a position believed to indicate paradoxical sleep. If the giraffe wants to bend down to drink, it either spreads its front legs or bends its knees. Giraffes would probably not be competent swimmers as their long legs would be highly cumbersome in the water, although they could possibly float. When swimming, the thorax would be weighed down by the front legs, making it difficult for the animal to move its neck and legs in harmony or keep its head above the surface.
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Famous quotes containing the word posture:
“If ones posture is upright, one has no need to fear a crooked shadow.”