Original photo by David Havel/ Shutterstock
As evidenced by Moo Deng, the pygmy hippopotamus whose pint-sized appearance and big personality took the internet by storm, hippos can be adorable. They’re also highly unusual creatures for several reasons, including the fact that their sweat is red. Some biologists disagree with calling it “sweat” because it serves a different purpose, moisturizing the animals’ skin and repelling water rather than cooling them down, but no one denies the color — it’s even sometimes known as “blood sweat.” In fact, the ancient practice of bloodletting stemmed from ancient Egyptians’ mistaken belief that hippopotamuses intentionally injured themselves when they were sick in order to drain their veins of apparently bad blood.
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It's a factDespite being herbivores, hippos are highly aggressive and are responsible for the deaths of around 500 people a year.
It took several years to safely and accurately figure out why this substance is red, as hippopotamuses, despite their endearing appearance, are in fact quite dangerous. Chemists eventually discovered that, when first secreted, the sweat is actually clear. It doesn’t turn red until it’s exposed to air, which reacts with two molecules aptly named hipposudoric acid and norhipposudoric acid to give the sweat its distinct hue. Depending on how further studies go, the substance may have useful applications for humans one day — it apparently works quite well as a lip balm and could potentially even serve as an effective sunscreen.
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The name "Moo Deng" means ______.
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The name "Moo Deng" means bouncy pork.
Hippos are most active at night.
Though not nocturnal, hippos tend to be most productive at night. This is partly due to the weather, as they’re native to Sub-Saharan Africa and spend most of the day submerged in water to keep cool. After leaving their resting waters at dusk, they’ll spend as many as five hours per night foraging for food, sometimes 2 to 3 miles away, and sleep on land. Grazing tends to be a solitary rather than communal affair, with the notable exception being mothers still caring for their calves, and the herd finds its way back to the water in the morning.
Michael Nordine is a writer and editor living in Denver. A native Angeleno, he has two cats and wishes he had more.
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