"They say The Man from Nowhere elephant has a trunk for a hand; if you give it a snack, it takes it with its trunk." Like the children's song we sang when we were young, an elephant's trunk looks rough but is famous for its sensitive touch. It can pick up a flat tortilla without breaking it and grab even a single peanut. It has been found that the ability to use the trunk like a hand comes from as many as 1,000 whiskers.
A team led by Professor Katherine Kuchenbecker of the Max Planck Institute for Intelligent Systems in Germany said on the 13th in the journal Science that "advanced microscopy analysis of the whiskers on an elephant's trunk showed that the structures at the root and the tip are different, allowing the animal to sense contacted objects as if seeing them with its eyes." Researchers from Humboldt University of Berlin and the University of Stuttgart also took part in the study.
◇The physical structure of whiskers serves as sensors
The researchers analyzed the structure of elephant whiskers with advanced microscopes and compared them with the well-studied whiskers of mice. The biggest difference was flexibility. A mouse's whisker is stiff from base to tip. There are also separate muscles under the skin where the whiskers are embedded. Mice sweep their whiskers back and forth to detect objects. Elephants have no such muscles. That suggests they have an inherent ability to detect objects without moving their whiskers around.
Elephant whiskers are made of keratin, a structural protein like that in nails or hair. Keratin itself cannot sense touch. Instead, the whiskers are embedded in follicles surrounded by nerve cells. When a whisker touches an object and vibrates, nerve signals arise in the follicle. The researchers found that the elephant whisker's asymmetric structure, top to bottom, is well-suited to amplifying these nerve signals.
From an Asian elephant that died of natural causes at a zoo, the team extracted 5-centimeter whiskers and analyzed their internal structure down to the nanometer (one-billionth of a meter) using computed tomography (CT) and electron microscopy. The whiskers were flat and rectangular at both the root and the tip. But their internal structures differed. The root embedded in the skin had many micro-pores and was stiff, while the tip was dense and rubbery-soft, moving easily upon contact.
The team explained that this difference in whisker stiffness along its length amplifies changes in signal strength, allowing detection of the contact location across the entire whisker. Without active movement, elephant whiskers achieve a kind of built-in "physical" intelligence through material design that optimizes sensation. Each whisker is a precision sensor with its own decision-making function.
◇Potential applications for sensing in intelligent robots
In fact, elephants are known to be close to highly nearsighted compared with humans. They can see objects clearly only at distances of about 10 to 20 meters. Beyond that, they cannot distinguish fine shapes and sense only movement. Elephants also cannot freely turn their large heads, so they must turn around to see what is behind them. Their trunks equipped with whisker sensors compensate for these drawbacks.
The whiskers on an elephant's trunk also have self-protection. Elephant whiskers do not regrow, so losing even a single strand creates a permanent sensory blind spot on the trunk. The researchers said the tiny pores at the root help absorb impacts, preventing damage to the precision sensors.
The researchers plan to apply technology that mimics elephant whiskers to robots so they can explore their surroundings even in poor visibility, such as in bad weather or at night. As a preliminary step, they created enlarged replicas of elephant whiskers with a 3D printer.
Co-corresponding author Andrew Schulz said, "When we closed our eyes and tapped objects with an enlarged replica we call a 'whisker cane,' we felt different sensations at each point of contact," and added, "A biomimetic sensor with segment-by-segment differences in stiffness, like an elephant whisker, can provide precise information with almost no computing expense."
References
Science (2026), DOI: https://doi.org/10.1126/science.adx8981