FIG. 36.2 Sensory transduction, which converts an external stimulus into a change in membrane potential. (a) Chemoreceptors are located in the antennae of the luna moth; (b) mechanoreceptors below the cuticle of a roundworm; and (c) photoreceptors in the eyes of a vertebrate.
Photo sources: a. Rolf Nussbaumer Photography/Alamy; b. Sinclair Stammers/Science Source; c. Eyal Nahmias/Alamy.