Elephant mouths have whiskers but not where you think they would be — elephants are also “lefties” or “righties”
New York – While Julie Andrews famously sang about “whiskers on kittens”, a new study published in Annals of the New York Academy of Sciences shines a light on the role of elephant whiskers, and the impact of trunk-directed eating behavior on them. The study by Yildiz and colleagues reports that the locations and types of elephant mouth whiskers (“vibrissae”), as well as altered elephant mouth anatomy, differ from that of other mammals. These modifications appear to be in response to the evolution of an elephant’s distinctive method of eating.
Lower lip of a baby elephant (left). The whiskers are long at the front (X-ray image, top right) and small and dense at the sides (X-ray image, bottom right). This is how elephant whiskers differ from the whiskers of other mammals, which are short at the front and long at the sides. Figure: Yildiz et. al (2024)
Bernstein members involved: Michael Brecht
Most mammals have densely spaced small whiskers (microvibrissae) around the front of the mouth, and these sensory hairs help determine the fine details of food that helps with consuming it. Most mammals also have large whiskers (macrovibrissae) located at the sides of the mouth that help the animal orient its mouth in the direction of food and other sensory signals.
But in the elephant mouth the types of whiskers and their position are reversed: Side whiskers are small and densely packed, while long whiskers are at the front. Also, unlike most mammals, elephants do not insert food into the front of their mouth but do so laterally, where the small densely spaced whiskers are located.
Yildiz and colleagues discuss how the differences seen in elephants may be due to how they use their trunk—long marveled for its dexterity, complexity, and uniqueness. The unprecedented location and pattern of elephant mouth vibrissae, along with other changes to the elephant mouth — an upper lip–nose fusion to the trunk, a super-flexible elongated lower jaw, and loss of incisors — likely reflects the evolution of their specialized method of trunk-mediated, lateralized food delivery to their mouth.
Humans use their dominant hand (“lefty” or “righty”) for tasks such as putting food in their mouths. An elephant will use its trunk in a similar way, placing the food on either the left or right side of its mouth depending on which side is dominant — a trait the authors call “trunkedness”. Consequently, the microvibrissae on an elephant’s mouth will be worn-down on the side of dominance (left or right) of food delivery by its trunk.
“I have studied whiskers all my life, but I have never seen a mammalian mouth like this,” says Professor Michael Brecht from Humboldt-University Berlin, Germany, who directed the study. Brecht and his team believe that an elephant’s sideward food intake contributes to its trunkedness. They studied the types of jaw vibrissae using samples from deceased wild African elephants, tissue samples and CT scans of elephant calves, as well as anatomical and behavioral measurements from captive Asian elephants to determine their findings.
Elephants are considered evolutionary gems because of their imposing size, distinctive trunk, and high intelligence. But poaching and habitat loss have rendered them endangered, and it is estimated that there are only 40,000 to 50,000 in the wild. Studies such as this create an appreciation and passion for these charismatic and remarkable animals, which is critical for advancing conservation efforts and supporting local economies through eco-tourism.
