Fig. 3.

(A) Diagram of time course of the acoustic startle response of 5–6 d.p.f. zebrafish, digitized from a representative positive response fish. The response is characterized by a fast, coordinated contraction on one side of the body, forming a distinctive C-shape (frame 4). Successive frames are 4 ms apart. (B) Diagrammatic representation of the four points marked throughout startle characterization: two eyes (green), caudal edge of the swimbladder (blue) and caudal fin (red). Point tracking was used to measure head–tail Euclidean length and head–midpoint–tail angle throughout responses.