The Giraffe is the world’s tallest land mammal, with males reaching heights of up to 18 feet tall. A giraffe’s legs can be up to six feet tall, and they can commonly live up to 25 years old. Male giraffes will utilize a behavior known as “necking”, and establish dominance with other males by smacking each other with their heads and necks. Their necks have 7 vertebrae, which is the same number a human has. Giraffes are currently undergoing a “silent extinction”, with their numbers declining almost 40 percent in the past 30 years.