# Electrophysiological and behavioral responses of elongated solifuge sensilla to mechanical stimuli

## TL;DR

This study explores how elongated sensilla on the legs of solifuge arachnids respond to mechanical stimuli, revealing they detect air pressure but not air movement.

## Contribution

The study identifies a mechanosensory function of elongated sensilla on solifuge legs, specifically their response to air pressure stimuli.

## Key findings

- Elongated sensilla on solifuge legs respond to air pressure but not air particle movement.
- Electrophysiological data revealed a fast-adapting mechanosensory cell in these sensilla.
- Behavioral observations showed a startle response to forceful air pressure stimuli.

## Abstract

A fundamental understanding of animal sensory systems is crucial for comprehending their interactions with the environment and with other conspecifics. However, knowledge gaps persist, particularly in arachnids like the order Solifugae. While certain solifuge setae and palpal papillae have been studied structurally and electrophysiologically, providing evidence of chemoreception and mechanoreception, the sensilla on their walking legs remain unexplored. Notably, elongated sensilla on the femur and tibia of the 4th walking legs resemble trichobothria in other arachnid orders yet their function remains unknown. Thus, this study investigates whether these sensilla serve a mechanosensory function. Using electrophysiological and behavioral assays on Eremobates pallipes (Eremobatidae), we assessed the response of the elongated 4th leg sensilla to– (i) air particle movement and– (ii) air pressure changes. Air particle movement stimuli were generated using a speaker placed in the near field of the elongated sensilla that emitted low-frequency pure tones (10–1000 Hz). Air pressure stimuli involved forceful blowing on the sensilla. No response to air particle movement was observed, but a mechanosensory response to air pressure stimuli was detected. Electrophysiological data identified a fast-adapting and fast-recovering cell, and behavioral observations revealed a startle response. Our electrophysiology results suggest a mechanosensory role of elongated sensilla on the 4th walking legs of solifuge, indicating that although they are not sensitive enough to detect air particle movement stimuli, they can receive and respond to air pressure stimuli. Our behavioral experiments similarly show that these sensilla are not sensitive enough to detect air particle movement but respond to more forceful mechanosensory stimuli.

The online version contains supplementary material available at 10.1007/s00359-025-01731-y.