An additional reason to think this theory is true lies in the tongue, as the base and back areas of the tongue are pink in color.
How the Giraffe Got Its Spots: A Genetic Just-So Story
Spots are common in the animal kingdom. Birds, insects, reptiles, fishes, and of course mammals sport spots.
In Darwinian terms, a trait persists because it provides a benefit that leads to reproductive success – the essence of natural selection. The benefit isn’t always obvious to us. Two years ago DNA Science covered the case of an anteater’s scales – genome sequencing revealed that what looks to us like armor actually provides an immune response to skin infections.
Rudyard Kipling’s (1865-1936) Just-So Stories famously explained “how the leopard got its spots,” “how the camel got his hump,” and “how the rhinoceros got his skin.” The ideas of Kipling, a journalist, writer, poet, and novelist, seem superficially to echo those of Darwin and Lamarck in pondering evolutionary advantages of inheriting traits distinctive for a species, but diverge in attributing a purpose and goal to changes driven by natural selection. Biology doesn’t work that way.
Now joining the list of the leopard’s spots, camel’s hump, rhinoceros’ skin and pangolin’s scales is the giraffe’s markings. The new report, “Seeing spots: quantifying mother-offspring similarity and assessing fitness consequences of coat pattern traits in a wild population of giraffes,” published in the journal Peerj, uses image analysis and statistics to fashion “a new quantitative lexicon for describing spots.” It’ll remain to others to sequence more giraffe genomes to figure out whether the animal is of a single species with nine subspecies, or four species.
Derek Lee from Wild Nature Institute, Concord, NH; Douglas Cavener from Penn State; and Monica Bond from the University of Zürich photographed the hides of 31 maternal-calf pairs of Masai giraffes, deducing who went with whom by following their subjects from the nursing stage. Giraffe moms don’t feed the young of others. Masai giraffes, the most populous subspecies, are native to East Africa.
A giraffe’s spots and blotches are superimposed upon dark grey skin. The pattern arises from an initial distribution of melanin-producing cells in the embryo, and later on, where and to what extent the melanocytes release their dark pigment.
The study assessed 11 spot traits, including number, area, perimeter, diameter, shape, circularity, color, shade, size, and jaggedness versus smoothness. Helpfully, as the animal grows, the spot pattern remains distinctive.
To standardize the photos and avoid counting speckles instead of spots, the investigators marked rectangles on the images of the hides and designated a unit of a certain number of pixels in height a “GU,” for “giraffe unit.” For a measurable trait they tracked survival, to test the hypothesis that certain coat patterns protect the babies. They also followed the young through four stages, from 2012 to 2016, using a capture-mark-recapture protocol.
The gist of the statistics was to assess how similar maternal spot patterns were to those of their offspring. If surviving calves more closely resembled their mothers than did calves that didn’t make it, then heredity likely influences the variability of spot pattern.
The analysis showed that newborn giraffes with larger, rounder or slightly irregular but smooth spots with solid colors were more likely to survive their first few months than differently adorned juveniles. Spot pattern can provide protection in a number of ways. “Giraffe spot patterns are complex and can be quite different among individuals. Complex markings can help animals evade predators, regulate their temperature, or recognize family or individuals, all of which can affect their ability to survive and reproduce,” said Lee.
Like zebras appearing to vanish with the visual effect of motion and light on their stripes, so too can spots and splotches provide camouflage. “Giraffe calves spend much of their time, day and night, hiding in the dappled light of trees and bushes and their ability to match this background should influence detection by visually hunting predators such as lions and hyenas,” write the researchers. Sharing a distinctive coat color pattern might help family members recognize each other for social interactions yet avoid mating with each other.
“Dr. Anne Innis Dagg, the first giraffe field researcher in Africa, presented evidence in 1968 that the shape, number, area, and color of spots in giraffe coat patterns may be heritable, but her analysis came from a small zoo population. We used wild giraffes and modern imaging and analysis techniques to confirm her conclusions,” said Bond, a graduate student in evolutionary biology and environmental studies.
We humans pride ourselves on our use of language, our technology and inventions, and our abilities to investigate the abilities of other species. The new work adds to ways that we can understand the meaning of coat color patterns in the wild, continuing the observations of Darwin, Lamarck, and Kipling.
(A semantic aside. The measure “heritability” estimates the degree to which genetics contributes to the variability of a trait – not to the trait itself. This is almost always misreported – even the authors of the new paper do so in the news release quoted above.)
The Sacramento Zoological Society, Columbus Zoo and Aquarium, Tulsa Zoo, Tierpark Berlin, The Living Desert Zoo and Gardens, Cincinnati Zoo and Botanical Gardens, and Save the Giraffes supported the work.
Giraffe Facts, Habitat & Lifespan
Instructor: Tanya Hausman Show bio Tanya has taught for 21 years, anywhere from 1st through 9th grades, as well as STEM. She has a bachelor’s in elementary education with a middle school math endorsement from Oklahoma Wesleyan University. She has a current professional teaching license and years of experience creating interesting, engaging lessons for her students.
Learn about the animal, giraffe, and study its physical features. Explore giraffe facts, such as what giraffes eat and examples of places where giraffes live. Updated: 08/09/2022
Table of Contents
- What is a Giraffe?
- Giraffe Facts & Characteristics
- What Do Giraffes Eat?
- Giraffe Habitat
- How Long Do Giraffes Live?
- Lesson Summary
What is a Giraffe?
The giraffe is a long-necked, hoofed mammal that lives in Africa. It is well-known for its unusual height. It has a long neck, long legs, and a distinct spotted pattern on its coat. It is in the Giraffidae family of mammals, and its scientific name is, Giraffa camelopardalis. Its scientific name came about because people thought it was a cross between a camel and a leopard, due to its coloring which is similar to a leopard and the small hump on its back.
An adult giraffe in Kenya.
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Giraffe Facts & Characteristics
Giraffes have a coat of irregular brown patches on a lighter background. Fur colors can vary from light tan to an almost black color. The coloring is a result, in part, of their diet and where they live. A giraffe’s markings are as unique to each animal as a person’s fingerprints, though giraffes that live in the same area do appear similar to one another.
Giraffes have a slight hump on their backs. Both males and females, have two hair-covered horns on their heads called, ossicones. Their tail has a long black tuft of hair on the end, and the tail can be 40 inches (1 meter) long. They also have a short brown or black mane that goes down the length of their neck.
In many countries, the giraffe population is declining. This is due to habitat loss, overgrazing from livestock, and poachers. The species was considered to be of least concern by the International Union for Conservation of Nature until 2016 when it was changed to vulnerable. A study done that year revealed that giraffe populations in some countries had declined by almost 30 percent in the past 20 years. Some countries have started giraffe conservation programs and others keep giraffes safe on wildlife reserves. Many zoos around the world work with conservation efforts to protect these creatures.
How Tall is a Giraffe?
The giraffe is the tallest mammal in the world. The neck alone is around 6 feet (1.8 meters) long and weighs 600 pounds (272 kg). It contains seven neck vertebrae, just like humans, but with a big difference. Each vertebrate in a giraffe’s neck can be 10 inches (25.4 centimeters) long. A giraffe’s legs are around 6 feet (1.8 m) in length. Females can be as tall as 14 feet (4.3 meters) and weigh up to 1,500 pounds (680 kg). A male giraffe can be 18 feet (5.5 meters) tall and weigh up to 3,000 pounds (1,360 kg). Giraffes do not have to compete much for food, since their height allows them to reach tender branches and leaves high up in the trees, higher than most other plant eaters can reach.
Everything about the giraffe is extra large. The heart alone is about 2 feet (0.6 meters) in length and weighs around 25 pounds (11 kg) and its lungs are big enough to be able to hold 12 gallons (55 liters) of air. Its feet are the size of dinner plates, around 12 inches (30.5 cm) in diameter. Even their eyes are large, being about the size of a golf ball.
Giraffe Tongue
Giraffes are not only well-known for their height, but also for their long tongues. Their tongues are 18 to 21 inches (46 to 53 centimeters) long and help them reach food. The tongue, as well as the inside of the mouth, is covered in a tough tissue to protect it. The tongue is a black or dark purplish color. It is believed that the dark color is able to protect their tongues from getting sunburned, as they feed most of the day.
The tongue of a giraffe is a dark color to protect it from the sun.
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Are giraffes the only animals with blue tongues?
Giraffes are not the only animals with blue or significantly dark tongues, there are other animals with similar characteristics, but the reasons may vary depending on which animal you look at.
The polar bear is one of them. Although the polar bear’s tongue is, strictly speaking, an extension of its fur, it is also dark.
However, polar bears are not born with a tongue with these characteristics; their tongue is pink when they are born and gets darker as they grow.
Eastern blue-tongued lizards, as their name suggests, also have blue tongues.
But these lizards use their tongues to ward off predators since when they feel threatened; they show their tongues to scare off their enemies.
The okapi is another animal with a blue tongue, but in this case, the trait they share with giraffes is even closer.
The okapi is closely related to giraffes but it doesn’t stop there. The okapi’s tongue is blue for the same reasons as giraffes.
Chow-Chow dogs also have blue tongues, but the reasons why they have blue tongues are unclear.
Meanwhile, the blue-tailed lizard also has a blue tongue, but they use it to distract birds and escape.
Impala also has a blue tongue. It is estimated that the reasons may be the same as those of giraffes.
Giraffe tongue length
Giraffe tongues have an impressive length, ranging from 18 to 21 inches (45.72 to 53.34 centimeters). But this is to be expected since the size of their tongue has proportions that correspond to the giraffe’s body.
The great length of their tongues enables giraffes to reach the tallest leaves, particularly those of acacia trees, which are among their favorites.
Again, the tongue length is not a surprise because giraffes are animals of large proportions throughout their bodies.
Adult male giraffes can reach up to 18 feet (5.49 meters), while females can measure up to 14 feet (4.27 meters).
Not to mention their weight, an adult male giraffe can weigh up to 3,000 pounds (1,360.78 kilograms) and females about half that.
Giraffes’ tongues and their influence on their diet
Giraffes have considerably long tongues, but this is an advantage when feeding. Giraffes have the leaves of acacia trees among their favorites, but it is a tall tree with branches containing many thorns.
Thus, giraffes can use their large tongues to reach the acacia leaves without contending with the thorns.
Considering that giraffes spend about 12 hours a day feeding, it is possible to say that their tongue greatly influences their survival in the animal world.
The particularity of giraffes and their diet is that they have no competition. No other animals in their natural environment can reach the same acacia leaves as giraffes.
All other animals are limited to eating the lower leaves, so giraffes can eat what and when they want since no one can overtake them.
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