Figure 1. Mating in the male C. elegans is a multi-step behavior.

(A) The male switches between behavioral motifs using inputs from tail sensory organs including 9 pairs of sensory rays (pseudo-colored green) with two neurons each, the hook (blue) with two sensory neurons, two postcloacal sensilla (pink) with three neuron pairs, and two phasmids (aqua) with three neuron pairs (B). (C) A tracking microscope simultaneously recorded male behavior and neuron activity a nuclear-localized calcium indicator (GCaMP6s) and a red fluorescent marker (mNeptune). Fluorescent hermaphrodites were used to track behavior. (D) An ethogram showing a behavioral trajectory for a single mating. (E) Continuous behavioral features were extracted from animal movements. (F) The activity of all visible neurons in the tail was continuously recorded. Most neurons could be identified. See also Video S1, Figure S1, Table S1 and S2.