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Hippo Milk: The True Story of Why It's Pink

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Many have heard the rumor that hippopotamus milk is unique in the animal kingdom, if only for its color. This belief has spawned memes, "fact checkers" and social media "fact posters" that are either misguided or downright wrong. In fact, one of the world's most famous popularizers of science may have contributed to some of the controversy surrounding this potentially pink substance. Well, let's take a look and find out: Is hippo milk pink?

Is hippo milk really pink?

The True Story of Hippo Milk and Why It's Pink
Hippo milk is not pink, but there was quite a bit of controversy surrounding it a few years ago.

© Frank Wouters / Creative Commons

Obviously, no. Hippo milk is not pink. While we might wish the rumors were true (if only for novelty's sake), they're not. However, some interesting information surrounding the rumor could lead to a source of false ideas. Let's take a deeper look.

Where did this idea come from?

Hippo milk - man feeding hippopotamus

©Oleg Golovnev/Shutterstock.com

While the idea may not be new, it has gained popularity with the public in recent years. When some social media circles started posting "facts" with the "fun fact" that hippo milk is pink, the real rumor started to circulate. No one seemed to be lying, so it started trending on different platforms like Twitter and Facebook. Still, the big rumored breakthrough is yet to come. That happened in 2013.

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Nearly a decade ago, 2013 was the new era of social media, and misinformation wasn't really understood. This was well represented in a July 26, 2013 National Geographic Facebook post. They posted this:

National Geographic, a science media company, was wrong. However, once Nat Geo released the "facts," it quickly became ubiquitous. Typically, accounts post photos of strawberry milk and refer to it as "hippo milk," backed up by a post from one of Science Talk's leading contributors. However, if the truth is not true, how did it come about?

Hippo milk may be the origin of pink

Hippos are aquatic animals that only come ashore briefly (in fact, they are distant relatives of whales). As mammals that live near water, they have developed some particularly interesting anatomical features to help them adapt better.

Hippos have special glands in their skin that secrete oils and fluids that look like sweat to humans. This oily secretion comes from their glands and forms a film on their skin. The film is transparent but turns reddish when it is exposed to UIV rays from sunlight. This discharge is often called "blood sweat."

This blood and sweat (reddish) may have been accidentally mixed into the milk of the baby hippopotamus that was feeding. This combination produces pink milk, but that's not on purpose. In addition, it is possible that a baby hippo covered in a little milk will turn red due to the secretion of an oily substance. Still, no matter how it officially appears, the rumor isn't true.

What is blood and sweat?

Hippo Milk: The True Story of Why It's Pink
Hippos secrete an oily substance that turns red when combined. This may lead people to believe that hippo milk is pink.

©Larry D. Moore/Creative Commons

Blood and sweat is a combination of hipposudoric acid and norhipposudoric acid. When the two combine, they are secreted from special glands in the hippo's skin. Hipposudoric acid is more reddish in color and norhipposudoric acid is more orange in color. Let's see what these two acids do.

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Hippos' skin is usually gray to blue-black, and their heads are brown and pink. Because the sun in sub-Saharan Africa (where hippos live) is so intense, adjustments are necessary to protect their skin. Sweat is primarily used as sunscreen, blocking UV radiation and preventing hippos from getting burned. Since they do not have any fur or hair to cover their bodies, this adaptation is essential.

The light-absorbing range of the two acids peaks near the ultraviolet region, allowing them to absorb harmful light without reaching the hippo's skin.

In addition, these acids act as antibiotics, killing potential growths that may make their home on the hippo's skin. This adaptation is remarkable because hippos live in an environment prone to bacteria. The likely source of these acids is the synthesis of the amino acid tyrosine, suggesting that this secretion is not dietary. This allows hippos to produce "sweat" no matter where they are.

Overall, blood sweat keeps hippos cool, blocks their skin from harmful UV rays, acts as sunscreen, and is an antibiotic that stops bacteria from growing. They may not have milk, but this is some very useful stuff!

What color is hippo milk?

As boring as it sounds, hippo milk is white. Rumors of pink hippo milk likely came from white hippo milk being accidentally splashed onto the red discharge of baby hippos. The resulting color should be pink.

Fun Facts About Hippo Milk

Hippo Milk: The True Story of Why It's Pink
Hippo milk was understudied, which eventually led to problems with premature hippos in captivity at the Cincinnati Zoo.

© nataliatamkovich/Shutterstock.com

It's not pink, but it's really interesting!

Hippo milk is high in calories. In order for babies to grow as fast as possible (up to around 3,300 pounds), they need a lot of calories. A cup of hippo milk has 500 calories per cup, according to one source, but there isn't much information on that.

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Most feeding takes place in water (at least in the wild), which means baby hippos usually nurse while completely submerged.

A few years ago, baby hippopotamus Fiona was born. Fiona was born prematurely, but she was cared for by a team of caretakers at the Cincinnati Zoo. During their research, they learned that hippo milk contains a lot of protein but is usually low in fat and sugar. The closest animal milk to a hippopotamus? Giant anteater milk.

So little research has been done on hippo milk that zookeepers have trouble even coming up with a basic formula. There's so little research, they're basically guessing and hoping things work out. After monitoring Fiona's vital signs and samples, they began working on the specifics of "premium hippo milk."


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Hippo milk - pink milk

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about the author

Colby Maxwell

Colby is a freelance writer from Charlotte, North Carolina. When he's not distracted by the backyard bird feeder, you can find him camping, exploring, and telling everyone around him what he's learned recently. There's a whole world to learn, and Colby is content to spend his life learning as much of it as he can!

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