Hair bundles
Hair bundles are the ear's detectors. (a) The bundle in this hair cell from a turtle is a pyramidal structure composed of stereocilia, which are connected by tip links.
(b) When the bundle is displaced, the tip links get stretched and pull open the transduction channels, thereby generating an electrical signal due to positively charged ions. Myosin motor proteins attached to the channels may be involved in active amplification. (Picture credit: Carole M Hackney/Keele University; see Fettiplace et al. in Further Reading)