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Alison Cherry's avatar

Hippopotamuses can't swim--they just walk across the bottom of a body of water. They can stay submerged for 5-6 minutes.

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NickS (WA)'s avatar

Here's a random animal fact -- the wrinkles on an Elephant's trunk are formed in utero:

https://www.science.org/content/article/how-elephant-got-its-wrinkles

"Many baby animals—including humans—are born with random wrinkles because they have too much skin for their body shapes. Baby elephants’ trunk creases, by contrast, are consistently in the same places and form before birth, suggesting they have a specific purpose. “We think these wrinkles are very underrated,” Brecht says.

To learn more, Schulz, Brecht, and their colleagues turned to two elephant species, Asian elephants (Elephas maximus) and African elephants (Loxodonta africana), which are known to use their trunks in different ways. African elephants have two tough cartilage “fingers” at the ends of their trunks that allow them to pinch objects. Asian elephants, by contrast, have one finger and one bulbous projection that they use to clamp large objects such as melons between their trunks and lower lips.

The researchers examined differences between the species in museum specimens, zoo animals, and photos. Asian elephant trunks, they found, contain more wrinkles: 126 of them, on average, compared with the 83 of African elephants. The extra creases might give the Asian species more flexibility to make up for not having an extra “finger,” Schulz says. In both species, the wrinkles were concentrated at a pivot point, which works like a muscular elbow to allow the trunk to wrap around objects.

To study how these wrinkles form, the team gathered two Asian and three African elephant fetuses in museum collections, along with dozens of published photographs or drawings of fetuses at different ages. By lining these up sequentially, the researchers were able to form a visual timeline of prenatal trunk development. Wrinkles, they found, begin to appear as soon as the trunk does—about 20 days into the elephant’s 22-month gestation. Over the next 150 days, the number of wrinkles increases exponentially in both species, doubling every 3 weeks, and concentrates around the pivot point. Asian elephants acquire even more wrinkles later on in development."

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