Standing close to 20 feet tall, giraffes have long necks that allow these African natives to reach the very tops of trees for food. Yet giraffes' necks have only seven vertebrae, which is about the same number of vertebrae as most other mammals. Giraffes' long necks filled with just a few bones have caused the animal to develop some unique anatomical features.
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Vertebrae are the individual bones that run the length of the back. The bones support and protect the spinal cord, which sends information from the brain to nerves throughout the body. The vertebrae also connects the torso and rib cage to the hip bones.
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Despite its size, a giraffe's neck has the same number of vertebrae as a human neck--seven. In fact, most mammals have this in common.
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The Unique Giraffe Neck
Each vertebra in the giraffe's neck can be up to 10 inches long. Added together, these seven bones, along with the head, can weigh up to 272kg. In order to support this tremendous weight, giraffes have developed unique vertebrae that fit together as ball-and-socket joints. (Humans have this type of joint in our shoulders.) Human vertebrae, on the other hand, are connected in the front and back, which allows limited movement.
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In order to carry the 272kg. of their head and neck, giraffes move differently than other mammals. Their stride is a lateral movement with the legs on one side moving together. As a giraffe takes a step, its head sways back and forth so its weight is supported throughout its stride. The neck acts as its centre of gravity.
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Getting Blood to the Head
Another consequence of its long neck involves getting blood to the head. Giraffes have a much higher blood pressure than humans--almost double--which keeps the blood pumping to its long extremity. Also, giraffes have larger hearts, which also help keep their blood flowing adequately, and special valves in their blood vessels keep their blood pressure at a proper level, even when they raise or lower their head suddenly.