title: Avoidance of a moving threat in the common chameleon (Chamaeleo chamaeleon): rapid tracking by body motion and eye use.
abstract: A chameleon (Chamaeleo chamaeleon) on a perch responds to a nearby threat by moving to the side of the perch opposite the threat, while bilaterally compressing its abdomen, thus minimizing its exposure to the threat. If the threat moves, the chameleon pivots around the perch to maintain its hidden position. How precise is the body rotation and what are the patterns of eye movement during avoidance? Just-hatched chameleons, placed on a vertical perch, on the side roughly opposite to a visual threat, adjusted their position to precisely opposite the threat. If the threat were moved on a horizontal arc at angular velocities of up to 85°/s, the chameleons co-rotated smoothly so that (1) the angle of the sagittal plane of the head relative to the threat and (2) the direction of monocular gaze, were positively and significantly correlated with threat angular position. Eye movements were role-dependent: the eye toward which the threat moved maintained a stable gaze on it, while the contralateral eye scanned the surroundings. This is the first description, to our knowledge, of such a response in a non-flying terrestrial vertebrate, and it is discussed in terms of possible underlying control systems.
authors.affiliation: Department of Evolutionary and Environmental Biology, University of Haifa, 199 Aba Khoushy Ave., Mount Carmel, Haifa, Israel.
authors.forename: Tidhar
authors.initials: T
authors.lastname: Lev-Ari
authors.affiliation: Department of Neurobiology, University of Haifa, Haifa, Israel.
authors.forename: Avichai
authors.initials: A
authors.lastname: Lustig
authors.affiliation: Department of Neurobiology, University of Haifa, Haifa, Israel.
authors.forename: Hadas
authors.initials: H
authors.lastname: Ketter-Katz
authors.affiliation: Keren Karev Educational Fund, Yavne-el, Israel.
authors.forename: Yossi
authors.initials: Y
authors.lastname: Baydach
authors.affiliation: Department of Evolutionary and Environmental Biology, University of Haifa, 199 Aba Khoushy Ave., Mount Carmel, Haifa, Israel. katgad@gmail.com.
authors.forename: Gadi
authors.initials: G
authors.lastname: Katzir
mesh_terms: D000818:Animals; D001362:Avoidance Learning; D001522:Behavior, Animal; D005133:Eye Movements; D007323:Instinct; D008116:Lizards; D009039:Motion Perception; D009043:Motor Activity; D012399:Rotation
keywords: Chameleon; Eye movement; Role-dependent eye movement; Threat avoidance; Visually guided tracking