Giraffes are the tallest mammals in the world and are best-known for the length of their neck, which is hypothesized to have evolved in order to provide the giraffe a competitive advantage in accessing the elevated foliage of trees. The giraffe’s neck requires a complicated internal anatomy that consists of many specialized systems that have evolved in order to maintain it.
The Outstanding Feature of a Giraffe: The Neck
The giraffe’s neck is six feet long and contains seven vertebrae, each one more than 10 inches long. The neck muscles of the giraffe weigh about 600 pounds. At the base of the neck, the vertebrae have spines that project upward, and these serve to support the neck muscles as they keep the giraffe’s head aloft.
The Heart and Cardiovasular System
The heart of a giraffe is enormous, weighing as much as 25 lbs. It needs to be this large in order to pump oxygen-rich blood 10 feet up to the giraffe’s brain. The giraffe’s body has a complicated system in place to control the immense blood pressure required, including reinforced artery walls, bypass and anti-pooling valves as well as a complex capillary network located at the base of the giraffe’s brain. This capillary network keeps the flow of the blood to the brain maintained at an adequate pressure, thus preventing potential damage from high-pressured blood rushing into the brain when the giraffe bends to take a drink of water.
The giraffe’s lungs are also large, about eight times the size of a human lung and able to hold up to 12 gallons of air. The respiratory rate of the giraffe is only about 1/3 that of a human. This slow respiratory rate is necessary so that the giraffe can inhale a large volume of air without causing damage to its trachea, which is 12 feet long.
The bones in a giraffe’s limbs are incredibly dense, and the skin on them is tough and contains a thick inner fascia (connective tissue), all of which aid in keeping the giraffe’s blood from pooling in its legs. In order to prevent the extreme bleeding that could occur due to the high blood pressure in a giraffe, all arteries and veins in its legs are deeply internal.
Tongue and Stomach
A giraffe’s tongue is approximately 18 inches long, which aids in its being able to maneuver around the thorns of the acacia trees that giraffes tend to favor. A giraffe’s saliva is thick and tacky in order to coat thorns which may inadvertently be swallowed. The giraffe is a ruminant--a mammal that digests plant-based food, such as leaves, by softening it within one section of its stomach, then regurgitating the partially digested mass, referred to as “cud,” in order to chew it again. A giraffe’s stomach contains four compartments to aid in this digestive process.