1. Why Is the Tongue So Long?
The long tongue helps giraffes reach leaves high up in trees. It also helps them pick leaves that are located between thorns. Sources explain that the tongue and lips work together to wrap around branches and pull leaves into the mouth [1]. Japanese encyclopedias also describe how the tongue wraps around leaves in high places to bring them to the mouth [3].
There is some variation in the reported length. A giraffe conservation group states the length is 45 to 50 cm (18 to 20 inches) [1]. A Japanese encyclopedia notes it reaches about 45 cm (18 inches) [3], while a science magazine article says about 50 cm (20 inches) [2]. Because sources differ slightly, this article uses the range of 45 to 50 cm (18 to 20 inches).
It is important to note that no study in the provided sources directly investigated why the tongue evolved to be this long. Being useful for eating is different from being long because of that need. Therefore, we cannot say for certain that the length evolved specifically for this purpose.
2. How Do the Tongue and Lips Work Together?
Giraffes extend their tongues between thorns to wrap around a branch. They then strip off the leaves while leaving the thorns behind. This action is described as the tongue working "like a hand" [1].
A Japanese encyclopedia explains that giraffes use their flexible lips in coordination with the tongue to avoid thorns while eating [3]. For thorny plants like acacia, the tongue and lips separate the leaves from the thorns [4].
You can imagine using your hands and fingers to pick petals from a thorny rose branch. In the case of a giraffe, the tongue and lips perform this delicate task.
3. What Is the Tongue’s Surface Like?
People who have touched a giraffe’s tongue at a zoo describe the surface as much rougher than they expected [4].
The surface is covered with small bumps called papillae. These bumps are thick, and explanations describe them as acting like armor to make it hard for thorns to pierce the tongue [1]. However, calling it "armor" is a description used in explanations. How much the papillae actually prevent injury is something that needs to be verified in the future.
Inside the mouth, sticky saliva covers the food. The food is then crushed against the grooved roof of the mouth before being swallowed [3].
4. Why Is the Tip Dark and the Base Pink?
The color of a giraffe’s tongue varies in appearance, ranging from blue-black to purplish-black. The part inside the mouth, at the base, is pink [2]. This means only the part exposed to the outside is dark.
The most popular theory is that the dark pigment, called melanin, protects the tongue from the sun’s ultraviolet rays. This prevents sunburn [1]. The idea is that because the tongue is stretched out for long periods to eat leaves, it is easily exposed to sunlight.
However, this theory is not fully accepted. It is stated that it is not "100% accepted" [1]. A science magazine also writes that there is no confirmed explanation yet [2]. It is helpful to distinguish between a strong theory and a proven fact.
It is consistent with this theory that only the parts exposed to sunlight for long periods are dark in color [1].
5. What Do We Know and What Is Unknown?
Sources state that the tongue is about 45 to 50 cm (18 to 20 inches) long. We also know it is used to extend between thorns, wrap around branches, and strip off leaves [1].
There are two points that remain explanations rather than proven facts. First is the reason for the length. While it is explained as useful for reaching high leaves or leaves between thorns, no study has directly verified the evolutionary process. Second is the reason for the color. The sunburn prevention theory is strong, but it cannot be called a definitive rule [1][2].
If you read that "a giraffe’s tongue is black because of sunscreen," check if it says "it is thought that" or if it states it as fact. The strength of the claim can vary depending on the source, even for the same fact.
6. At Home and at the Zoo
At home, you can try this: Hold a 30 cm (12 inch) ruler against your arm, from the elbow to the palm. The giraffe’s tongue is much longer than this. It extends more than half a ruler’s length past your palm.
At the zoo, if you see a giraffe eating from a tree branch, watch how the tongue moves. Look at how it wraps around the branch, what the lips are doing, and if the color differs between the tip and the base. Writing down what you see can help you compare it with this article. If there is a feeding experience, follow the instructions of the zoo staff.
If you want to learn more, there are still few Japanese resources focused on the tongue. A report on the shape of the papillae by Japanese researchers is a starting point [5]. The reason for the color may change with future research.