The giraffe is the largest ruminant animal and the tallest land mammal, with an adult giraffe neck averaging a staggering 1.8 m / 6 ft in length! The main diet of the giraffe is tree leaves and buds. It has a prehensile tongue that is dark blue-black in color and is extremely long (45-50 centimeters or 18-20 inches). This construction allows the giraffe to nimbly wrap its tongue around the spiny thorns of the acacia tree and deftly remove the leaves without any harm to its mouth or tongue. Nine sub-species of giraffe are recognized, including the South African giraffe, Rothschild’s giraffe and Masai giraffe. The gestation period for a female is 14 months and they normally give birth to one young.