Por que as girafas têm línguas roxas

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Por que as girafas têm línguas roxas
Se alguém lhe pedisse para apontar para a parte mais estranha de uma girafa, você provavelmente não apontaria
para a boca. Suas figuras padronizadas, pescoços imponentes e marchas esbeltas os tornam animais bastante
únicos. Tendo como pano de fundo o Serengeti Africano, a silhueta de uma girafa é inconfundível – e, no entanto, eu
diria que é a sua língua longa e roxa que pode ser apenas a sua característica mais estranha.
https://www.zmescience.com/science/news-science/giraffe-species-08092016/
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Os saurópodes da nossa época: girafas! Imagem via Wikimedia Commons.
Você viu isso em passeios de safári e documentários sobre animais – um pescoço longo e gracioso que se estende
em direção aos céus, culminando em uma língua intrigantemente roxa. É uma das características mais intrigantes da
natureza. Mas por que, você pode se perguntar, uma girafa tem uma língua roxa?
Por que as girafas têm línguas roxas?
Duas palavras: o protetor solar da natureza.
Pense nisso – as girafas são megaherbivores. Basicamente, isso significa que eles são animais gigantescos que se
alimentam de plantas, como elefantes.
Eles também têm semelhanças com herbívoros menores, como vacas. Isso ocorre porque as girafas são
ruminantes; elas foram construídas para digerir a celulose, o material que compõe as paredes celulares das plantas.
Novamente, como vacas, eles passam muito tempo comendo e pastando por comida, mas a única diferença? As
vacas pastam grama do chão enquanto as girafas preferem pegar folhas nas copas das árvores. Eles não comem de
uma só vez, as girafas adultas podem passar mais de 20 horas por dia apenas andando, árvore a árvore e comer
em qualquer lugar entre 15 libras ou 75 quilos de folhas por dia.
Sob o sol escanteio, não é apenas o seu corpo que suporta o peso da exposição ao calor; suas línguas também.
Como as girafas passam a maior parte do tempo comendo, suas línguas, compostas de células epiteliais (o material
que compõe a pele), ficam fora da boca por cerca de 20 horas por dia também. Sem proteção, essa língua está
ligada a queimar.
https://cdn.zmescience.com/wp-content/uploads/2023/10/Giraffe_in_Mikumi_Park_Tanzania.jpg
https://www.zmescience.com/science/mega-herbivores-eco-engineers/
https://www.zmescience.com/ecology/pollution-ecology/cows-plastic-bacteria-05072021/
https://www.zmescience.com/medicine/nutrition-medicine/eating-lots-sugar-causes-gain-weight/
https://www.zmescience.com/science/archaeologists-find-mummies-in-egypt-with-golden-tongues-in-their-mouth/
https://www.zmescience.com/science/archaeologists-find-mummies-in-egypt-with-golden-tongues-in-their-mouth/
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Uma girafa a tirar-lhe a língua. Imagem via Wikimedia Commons.
Você pode pensar que a cor da língua não é um grande problema. Mas, no mundo científico, cada detalhe conta. A
língua da girafa não é apenas roxa; é um tom específico que se inclina mais para azul ou preto, dependendo da
iluminação. E essa tonalidade distinta não é uma escolha caprichra da Mãe Natureza. Ele serve a um propósito.
Para evitar um caso grave de queimaduras solares, as girafas abrigam uma adaptação bacana em suas línguas -
melanina.
Melanina, uma espécie de pigmento, é o material que torna a língua da girafa escura (roxo ou azul) colorida. Embora
ainda haja lacunas na pesquisa, os cientistas acreditam há muito tempo que essa tez escura da língua – devido a
uma alta densidade de melanina – é o que protege a língua da girafa dos intensos raios ultravioletas da savana
africana.
To make things interesting, only the anterior parts of the tongue — the prehensile part — are actually melanized! The
middle and posterior parts of the tongue are a run-of-the-mill, baby-pink color.
What’s up with giraffe tongues?
Giraffes tongues have a lot going on. Not only are they purple, but they’re also ridiculously long. An average giraffe
tongue measures in at about 50 centimeters – half a meter long!
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https://www.zmescience.com/ecology/environmental-issues/antropocene-060219/
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Again, this comes down to the fact that giraffes are mega herbivores. Giraffes have the distinct pleasure of having
almost no competition (except elephants) to contend with for their food. All that grows at heights of 15 feet and above
is theirs to eat — especially Acacia, a species of tree commonly found across the Serengeti.
Giraffes often have little to no competition for food. Image via Wikimedia Commons.
A food loved by both elephants and giraffes alike, Acacia leaves aren’t exactly the easiest thing to reach. Both leaves
and spines (sharp, pointy, and painful) adorn the branches of the tree. This alternate placement of leaves and spines,
poses may pose a threat to some species but to the giraffe — it’s no sweat.
The battle of tongue versus tree
To combat the prickly vegetation of the acacia trees, giraffes employ sneaky tactics. They use their elongated and
dexterous tongues to elude the prickly thorns of acacia trees; going straight for the leaves instead. Moreover, giraffes
have toughened papillae on their tongues, rendering the surface hardened and rough, thus providing further
protection against any potential harm.
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https://www.zmescience.com/ecology/environmental-issues/sapwood-water-filter-4042344/
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Acacias are also commonly referred to as thorn trees. Image via Wikimedia Commons.
Even If the razor-sharp thorns of the acacia manage to draw blood; it doesn’t matter. Giraffes produce antiseptic
saliva; it doesn’t matter if they get cut — they just lick themselves to get better!
Odd, not rare: other animals with darkened tongues
Although uncommon, purple or blue tongues have also been observed in other animals across a range of habitats.
From Polar bears to lizards, an odd assemblage of animals make up an eclectic group of purple-tongued animals.
Purple-tonged mammals
Okapi
Toss in a zebra, a giraffe, and a deer in a blender, and out comes an Okapi. Armed with the legs of a deer, the pattern
of a zebra, and the head of a giraffe, the Okapi is arguably one of the strangest animals alive today.
Yes, Okapis are real. Image via Wikimedia Commons.
Despite their confused appearance, Okapis (also known as Forest Giraffe) is the Giraffe’s only living relative (no, they
aren’t also related to zebra and deer). Similar to their cousins, they also possess the same distinctly colored
purple/blue tongues.
https://cdn.zmescience.com/wp-content/uploads/2023/10/DSC_7707y.jpg
https://www.zmescience.com/science/polar-bear-eats-dolphin-83784/
https://www.zmescience.com/science/biology/first-pictures-of-the-okapi-or-the-african-unicorn/
https://cdn.zmescience.com/wp-content/uploads/2023/10/Saint-Aignan_Loir-et-Cher._Okapi.jpg
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The Okapi and Giraffe are the only two extant members of the Giraffidae family. Image via Wikimedia Commons.
Okapis live in the canopied rainforests of Central Africa. Forget the sun, the canopy of these forests is so dense that
even raindrops don’t make their way to the forest floor. So, what gives with their darkened tongues? Well, it’s still all
about sunlight.
So how does sunlight make it to the ground in such a place? It all comes down to treefall gaps. Rainforests are
ancient. Trees in rainforests aren’t just decades old — there’s a good chance they are over half a century old. When
giant trees like these, with their behemoth girths, fall down, they leave a literal hole in the canopy. Through these
holes, emergesthe opportunity for new growth; and thus life on the forest floor.
It is in the grounds directly under treefall gaps that Okapis love grazing in; ironically the only area in a rainforest that
receives enough sunlight to warrant possessing some form of sunscreen. Again, similar to their cousins, Okapis have
prehensile and dexterous tongues that are long enough to clean their own ears.
Okapis can clean their ears with their long tongues. Image via Wikimedia Commons.
Polar Bear
It’s not just the hot places of the world that house purple-tongued animals; cold places have their share too. Up north
in the Arctic Circle, Polar Bears are another example of odd tongues in the wild. Interestingly Polar Bears aren’t born
with darkened tongues. As babies, they have the typical pink tongues that we do. Over time, this color darkens into a
https://cdn.zmescience.com/wp-content/uploads/2023/10/Copy_of_ap_bio_project-2.svg
https://www.zmescience.com/science/gabon-becomes-first-african-country-to-get-paid-for-protecting-its-forests/
https://cdn.zmescience.com/wp-content/uploads/2023/10/1024px-Okapi_tongue.jpg
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https://www.zmescience.com/feature-post/pieces/polar-bears-abandoned-photos-20042022/
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bluish-purple or black hue — the same shade as their skin. Yes, a polar bear’s skin is dark — it’s just its fur that’s
whiteish.
A Polar Bear sticks his tongue out. Image via Wikimedia Commons.
This shift to blues and blacks isn’t for the vibes. Think about it, the arctic is a cold, cold place; you need to conserve
and absorb as much heat from any source as you can. Of all the colors in the world, dark shades like blue — and
especially black –absorb the most light. This helps the bears stay warm — or better retain whatever warmth they
have.
Basically, unlike the Okapis and Giraffes of Africa, Polar Bears’ tongues aren’t dark to protect against sunlight but
rather to absorb it (funny how that worked out).
Fun fact: Neither their skin nor their fur is actually white! The Polar Bear has black skin and a translucent coat of fur
that looks white due to the light it reflects.
Purple-tongued reptiles
Certain reptiles, notably lizards, possess darkened tongues as well. Although not exactly purple, skinks, such as the
blue-tonged skink, are popular examples of colored tongues in the reptilian world. Luckily, a lot more research has
been conducted on the blue-tongued skinks than on Okapis, Giraffes, or even Polar Bear tongues.
Why do skinks have blue tongues?
For instance, a study from 2018, conducted by researchers at Macquarie University, Australia, found that lizards, like
the blue-tongued skink, employ their blue tongues as last-ditch measures against predators.
The lead author for the study, Arnaud Badiane, said that blue-tongued skinks use their colored tongues, in
conjunction with other aggressive displays like hissing to scare and disorient predators.
https://www.zmescience.com/science/polar-bear-hair-insulator-92352424/
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https://www.zmescience.com/ecology/polar-bear-swim-25042016/
https://www.zmescience.com/ecology/animals-ecology/bluetongue-skink-predator-8259710/
https://www.jstage.jst.go.jp/article/ofaj/89/4/89_99/_article/-char/ja/
https://link.springer.com/article/10.1007/s00265-018-2512-8
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A blue-tongued skink. Image via Wikimedia Commons.
“The lizards restrict the use of full-tongue displays to the final stages of a predation sequence when they are most at
risk, and do so in concert with aggressive defensive behaviors that amplify the display, such as hissing or inflating
their bodies,” said Badiane, in a press release.
Blue-tongued Skink attacks a Kookaburra figurine.
She further explained that this method of defense was especially effective against aerial predators like birds. “This
type of display might be particularly effective against aerial predators, for which an interrupted attack would not be
easily resumed due to loss of inertia, ” explained Badiane.
Another cool fact about these lizards’ tongues is that they’re not just blue — they have UV-blue tongues. Essentially,
when seen under ultraviolet light, their tongues radiate an even brighter, more conspicuous shade of blue.
Finally, the same study also stressed on the importance of timing when it came to these full-tongue displays against
predators. Badiane explained that for more intense attacks against predators, the lizards would expose a greater
section of their tongue, with the rear parts of their tongue, glowing a brighter shade of blue than the tips.
“If (full-tongue displays) performed too early, a display may break the lizard’s camouflage and attract unwanted
attention by predators and increase predation risk. If performed too late, it may not deter predators,” said Badiane.
A tongue-in-cheek conclusion
In the animal kingdom, tongues are more than just organs of taste and speech; they are versatile instruments shaped
by evolutionary necessity. From the sun-soaked savannas of Africa to the frigid Arctic tundras, from towering giraffes
to scurrying skinks, the colors, lengths, and textures of tongues reveal the remarkable adaptability of Earth’s
creatures. The giraffe’s purple tongue, a biological marvel that thrives under the unyielding African sun, encapsulates
this adaptability in a striking way.
We might not yet fully know why giraffes — or any of the many animals that have purple or blue tongues — have
darkened tongues however, we may take solace in the fact that giraffes certainly seem to be winning the battle of
tongue versus trees in the Serengeti.
So there you have it: the low-down on why a giraffe’s tongue is purple—it’s a full-blown survival tool. Who knew that
the secret to surviving the African heat was, quite literally, on the tip of a giraffe’s tongue?
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