From eating to breathing, smelling to bathing, drinking to communicating, the multifunctional elephant trunk exhibits a breathtaking flexibility and dexterity that has captivated humans for generations. While African elephants are larger than their Asian counterparts, the trunks of African elephants and Asian elephants share many features. Both elephants boast nearly 40,000 muscles in their trunks alone (humans only have ∼600 in total), allowing both large, forceful movements, but also impressively fine motor control akin to human hands. Overlaying the muscular trunk is a layer of skin, which serves as a form of protection, and, with the help of hundreds of whiskers lining the length of the trunk, assists the elephant in sensing its immediate surroundings. The skin is also enveloped in thousands of wrinkles, which facilitate extreme bending and wrapping. Andrew Schulz from the Max Planck Institute for Intelligent Systems and colleagues from Humboldt-Universität zu Berlin and Leibniz Institute for Zoo and Wildlife Research, Germany, sought to investigate the differences between the trunks of African and Asian elephants, to uncover what these wrinkles may tell us about how the world's largest land mammals engage with their environment and how that interaction helps shape the physical appearance of their trunks.
By using photos taken of adult elephants in both laboratory and zoo settings, the researchers first compared the number of wrinkles found on the trunks of African savannah elephants (Loxodonta Africana) and Asian elephants (Elephas maximus). They found that Asian elephants not only had more wrinkles across the entire trunk than their African counterparts, but they also have a larger concentration of wrinkles at the tip of the trunk. This is likely because of a key anatomical difference between the two species of elephants: African elephants have two finger-like bulges at the tip of their trunks that can pinch and manipulate objects, while Asian elephants do not. Instead, Asian elephants tend to wrap their trunks around objects, leading to a greater number of wrinkles on their trunks compared to African elephants.
The researchers also discovered that in both species the number of wrinkles on the left and right side of their trunks is dependent on their ‘handedness’ – or in this case – ‘trunkedness’. Yes, elephants are allowed, and do indeed have, a side preference just like humans. When reaching for an object, ‘left-trunked’ elephants will tend to wrap their trunk left, making contact with the object with the left side of their trunks. This trunkedness can be visualized on the skin of elephant trunks themselves. Researchers found 10% more wrinkles and relatively longer whiskers on the side of the trunk the elephants preferred to bend towards. This is because the opposing right side contacts the ground more often, which causes abrasions of its trunk and wear on its whiskers. Unlike human handedness, which is skewed for ‘righties’, trunkedness is not biased; left-trunked elephants are as common as right-trunked elephants.
This is a classic example of how an animal's appearance and movements are closely interconnected, with each influencing and reflecting the other. Inherent differences in the structure of the trunk tips, which allow African elephants the added ease of pinching rather than wrapping their trunk tips around objects, may explain why Asian elephants have more wrinkles than African ones. Similarly, the interaction between the elephants’ trunkedness, or how they tend to use their trunk in their environment, is also reflected in the number of wrinkles on either side of the elephant trunk. This means next time you get close enough to one of these majestic animals you can show off your latest party trick by taking a look at the wrinkles on the sides of the trunk, declaring, ‘This elephant is left-trunked!’
