Functional anisotropy of the elephant trunk skin: A biological blueprint for grasping, protection, and tactile sensing.
In collaboration with Lucia Beccai’s Soft BioRobotics Perception Lab at the Istituto Italiano di Tecnologia in Genova (Italy), we publish today in PNAS Nexus a new study elephants.
Using motion-capture technologies developed for the movie industry, we have previously demonstrated that the complex behaviours of the elephant trunk emerge from the combination of a finite set of basic movements such as the propagation of an inward curvature and the formation of pseudo-joints. In addition, we have shown that the elephant trunk velocity obeys a mathematical law observed in human hand drawing movements. These results were published in the journal Current Biology. Check also our elephant trunk project website.
In a new study published today in PNAS Nexus, we show that the Asian elephant trunk skin is not a uniform covering, but a functionally zoned and anisotropic biocomposite that helps solve a remarkable biomechanical paradox: how the trunk can be both robust enough for protection and flexible enough for delicate grasping.
By combining morphological analyses, mechanical testing, imaging, and finite-element modelling, the study reveals a strong dorsal–ventral dichotomy. The dorsal skin is rougher and 3.14 times stiffer, acting as a protective shield, whereas the more flexible ventral skin is specialized for conformal grasping. The ventral side also contains distinctive dermal papillae, which our models predict act as subsurface stress amplifiers, potentially enhancing tactile sensitivity without compromising durability.
These results suggest design principles for the next generation of artificial tactile skins: instead of relying on a uniform material, soft robotic grippers could benefit from a zoned architecture that combines protection, flexibility, and mechanically amplified sensing.
Much additional information is available in the original article:
Functional anisotropy of the elephant trunk skin: A biological blueprint for grasping, protection, and tactile sensing.
Lo Preti , Dagenais , Kamare , Bernardeschi , Lantean , Milinkovitch & Beccai.
PNAS Nexus, 2026, 5, p.164.
https://doi.org/10.1093/pnasnexus/pgag164