Mechanosensory Systems

Sensory system

The suite of structures involving detecting and processing specific signals from the external and internal environment

Stimuli

Signals from the external and internal environment

Dendrites

Neuron endings

Sensilla (singular = sensillum)

Sensory neurons are enclosed in this external structure

Sensory transduction

Sensory neurons convert stimulus into electrical signals

Action potentials

Changes in cell membrane voltage

Mechanosensory system

System specialized for sensing physical stimuli (i.e., those caused by mechanical forces)

Mechanoreceptors

Mechnosensory sensilla

Trichoid sensilla

Hair-like structure used to sense physical touch and airborne vibrations

Seta nestled in a flexible socket. When seta moves, sensory neuron anchored at the socket's base sends signals to the brain.

Campaniform sensilla

Dome-shaped structures that respond to deformations of the cuticle (caused by stretch, strain, pressure, and other forces)

Halteres of Diptera are covered in these sensilla! Helps with proprioception in flies

A dome is nestled in a bell-shaped socket. When pressure is applied to the dome, the dendrites attached underneath the dome send a signal.

Nociception

The ability to sense harmful stimuli

Nociceptors

Sensory neurons that sense harmful stimuli

Pain

Subjective emotional response to nociception - there is no strong evidence that insects perceive this the way humans do

Chordotonal organs

Collections of internal stretch receptors (typically found at the joints) that are important for proprioception

Proprioception

The body’s ability to sense its own position and movements

Johnston’s organ

Detects NEAR-FIELD sounds

Specialized chordotonal organ between the 2nd and 3rd antennal segments - unique to insects!

Auditory system

Specialized mechanosensory system that detects soundsO

Tympanum

Detects FAR-FIELD sounds

Flexible membrane that vibrates in response to sound waves

Underneath this structure are mechanosensory neurons to transduce the signal

Can be located (almost) anywhere on the insect body!

Stridulation

The act of producing sound by rubbing certain body parts together

PHONOtaxis

The act of recognizing and moving towards the source of an acoustics signalD

Duetting

Both sexes produce sounds to attract mates

Observed in cicadas, some katydids, and some grasshoppers