Fig. 1: Components of the fast-start escape response.

This study examined the role of social familiarity in the reaction timing and kinematic performance of schools of the tropical damselfish Chromis viridis, focusing on three key traits: latency, average turning rate, and distance covered. a Latency indicates the time period between the threatening stimulus breaking the water surface and the fish’s first movement, with a shorter latency indicating a faster reaction time. b Average turning rate is measured by dividing the angle achieved during the first unilateral bend of the reaction (i.e. stage 1) by the duration of time to achieve that angle, with a higher turning rate indicating greater agility in the response. c Distance covered indicates the distance moved during the first 42 ms of the reaction, the mean time period for individuals to complete two body bends (i.e. stages 1 and 2), and is indicative of the response’s speed and acceleration. In all panels a–c, the grey fish silhouette indicates the fish’s position immediately prior to stimulation and the black fish indicates the fish’s position during each component of the fast-start escape response.