The giraffe is known for its really long neck. Just like all mammals the giraffe has seven neck vertebrae. But at 28 centimeters each they are considerably larger than ours!
Thanks to its long neck it can easily reach the tastiest leaves of the acacia. This tree has sharp thorns on its branches to protect its leaves. With its long, dark-blue tongue the giraffe can still reach the leaves. When an adult male giraffe uses his tongue and stretches fully he can reach up to a height of 6 meters.
This long neck is not without problems though. To reach water its head has to hang down for a long time. The heart must make sure that the blood pressure is high enough to pump sufficient oxygen-rich blood to the head when it is in an upright position, but not so high that blood vessels burst when the giraffe holds its head down. To solve this problem the giraffe has special adaptations in the circulatory system. For example its blood vessels are highly flexible, so they can resist temporarily high bloodpressures.