American Scientist

On the Lookout

Giraffes are herbivores that live on the open savanna and in wooded grasslands in Africa. They tower above all other mammals—adult males can top out at 5.8 meters tall and weigh 1,270 kilograms, with necks up to 2.4 meters long. Giraffes require very high blood pressure to circulate blood through their tall bodies. A February 2021 study published in the Annual Review of Physiology outlines the unique characteristics of the species’ blood vessels, heart, and kidneys to compensate for this high blood pressure.

Other animals look to the giraffe for signs of distress because they are often the rst to detect danger from their sky-high perspective. Giraffes live in loosely bound, scattered herds of 10 to 20 members. According to an August 2021 paper in Mammal Review, the herds exhibit cooperative, matrilineal social groups that are maintained through complex communication systems.

Wide Range of View

Giraffes have the largest eyes of any land mammal. Keen eyesight is essential for spotting predators on the open savanna. The giraffe’s long eyelashes repel ants and sense thorns on the branches of the acacia trees that they eat.

Pattern

The irregular brown markings that cover most of its body are unique to each giraffe, like fingerprints in humans. The pattern offers some camouflage, but the markings are primarily used as thermal windows to regulate temperature. Each marking has a large blood vessel around its border. By directing blood flow to or away from the smaller vessels branching toward the center of the marking, the giraffe can radiate or retain heat as needed.

Fly Swatter

A black tuft on the end of the giraffe’s long, thin tail is an efficient fly swatter that keeps insects off the animal’s rump.

Strong and Flexible Neck

The bony structure of the giraffe’s neck demonstrates an excellent balance of weight, flexibility, and durability. Like humans, giraffes have seven cervical vertebrae, but theirs can grow more than 25.4 centimeters long. The vertebrae are joined by ball-and-socket joints that oer a 360-degree range of motion. The first and second thoracic vertebrae are also joined with a ball-and-socket joint, allowing additional flexibility. The joint between the giraffe’s neck and skull allows it to extend its head almost perpendicular to the ground. The neck sways with its stride, guiding its center of gravity, and the giraffe tosses its neck back and forth to help it rise from a sitting to a standing position on its spindly legs.

The vertebrae over the giraffe’s shoulders have long vertical extensions, which create its signature hump. Its nuchal ligament runs from the back of the skull to the base of the tail, and is thickest over the shoulders. This ligament acts like a giant rubber band, counteracting the weight of the giraffe’s head and neck. This mechanism causes the giraffe’s head to bob up and down when it walks and allows the animal to hold its head aloft without relying solely on muscular energy. Male giraffes, called bulls, compete through necking, in which they use their hefty necks to strike each other with crushing force.

Extra Support

The giraffe is a two-toed ungulate, or hoofed animal. A highly specialized structure prevents giraffes’ thin legs from collapsing under their immense weight. Elongated metatarsal and metacarpal bones account for roughly half of the leg’s length. A groove runs along the length of these bones, housing a structure called the suspensory ligament. This elastic tissue provides support so that giraffes can carry their weight with minimal muscular effort, reducing fatigue.

Giraffes have a pacing gait, moving both legs on one side at the same time, which causes them to sway back and forth when they walk. This gait saves energy by enabling longer strides. Giraffes can sprint as fast as 60 kilometers per hour in short bursts, and their powerful kick is strong enough to kill a lion.

Symbiotic Relationship

Red-billed and yellow-billed oxpeckers, or tickbirds, have a symbiotic relationship with giraffes. The oxpeckers eat ticks and parasites off the giraffes, and the giraffes are relieved of blood-sucking, disease-carrying parasites. The birds’ feet are adapted for grasping, which allows them to remain perched on their host while it moves through the savanna. The oxpeckers sift through the giraffes’ hair looking for insects, and they also clean the giraffes’ teeth.

Horns

Males may have up to five calcified occicones, or horns, that they use during fights for dominance.

46-Centimeter Tongue

Giraffes’ tongues add 46 centimeters to their reach, allowing them to snag their favorite snack: the leaves, pods, and fruits of acacia trees, which can grow to heights greater than 12 meters. Giraffes can eat more than 66 kilograms of leaves daily. The lips of the giraffe are made of tough skin that serves as protection from the tree’s thorny branches, and the roof of its mouth is grooved to help strip leaves off the tree.

The giraffe is the world’s largest ruminant, a group of animals that partly digest their food and then regurgitate it to chew as cud. Food is digested through a four-chambered stomach to maximize nutrient absorption. Because of their efficient digestive system, giraffes can survive for several days without water.

This infographic was created by Charlotte Ricker.