Giraffes use their long, prehensile tongues to extend their reach. Specimen at the National Museum of Natural History, Washington, DC.Giraffes are famous for their long necks which allow them to browse on the leaves of trees, and elongated forelegs (which are much longer than the hind legs). The bony structure of the neck is essentially unchanged from that of other mammals: there are no extra vertebrae, but each of the 7 bones is greatly enlarged. Bone constitutes the bud-like horns called ossicorns, which are covered with the Giraffe's skin like the rest of the skull.













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Modifications to the Giraffe's structure have evolved, particularly to the circulatory system. A Giraffe's heart, which can weigh up to 24 lb (10 kg), has to generate around double the normal blood pressure for a large mammal in order to maintain blood flow to the brain against gravity. In the upper neck, a complex pressure-regulation system called the rete mirabile prevents excess blood flow to the brain when the Giraffe lowers its head to drink. Conversely, the blood vessels in the lower legs are under great pressure (because of the weight of fluid pressing down on them). In other animals such pressure would force the blood out through the capillary walls: giraffes, however, have a very tight sheath of thick skin over their lower limbs which maintains high extravascular pressure in exactly the same way as a pilot's g-suit.

Images 1 Through 8 Are Courtesy of US Fish & Wildlife Service
Images 9 through 24 Are Courtesy Of Scotch Macaskill





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