The functional anatomy of elephant trunk whiskers

Behavior and innervation suggest a high tactile sensitivity of elephant trunks. To clarify the tactile trunk periphery we studied whiskers with the following findings. Whisker density is high at the trunk tip and African savanna elephants have more trunk tip whiskers than Asian elephants. Adult elephants show striking lateralized whisker abrasion caused by lateralized trunk behavior. Elephant whiskers are thick and show little tapering. Whisker follicles are large, lack a ring sinus and their organization varies across the trunk. Follicles are innervated by similar to 90 axons from multiple nerves. Because elephants don't whisk, trunk movements determine whisker contacts. Whisker-arrays on the ventral trunk-ridge contact objects balanced on the ventral trunk. Trunk whiskers differ from the mobile, thin and tapered facial whiskers that sample peri-rostrum space symmetrically in many mammals. We suggest their distinctive features-being thick, non-tapered, lateralized and arranged in specific high-density arrays-evolved along with the manipulative capacities of the trunk.

Automated summary

The study suggests that elephant trunks are highly sensitive to touch and mainly rely on whiskers for perception. Whiskers are more densely located at the trunk tip, with African elephants having more than Asian elephants. Adult elephants show worn-out whiskers on one side due to their lateralized trunk behavior. Elephant whiskers are thick, non-tapered, and arranged in specific high-density arrays along the trunk. They are innervated by approximately 90 axons from multiple nerves. Unlike facial whiskers in other mammals, trunk whiskers do not serve a symmetrical sampling function. The unique features of trunk whiskers are believed to have evolved alongside the manipulative capacities of the trunk.