Fig. 1. Successive ventral view images (100 ms apart) of a trout with an intact lateral line (A), showing an escape response to a sudden jet of water directed at the body from a syringe (asterisk indicates the start of the jet). Images correspond to the black bar on the graph of head velocity shown below (`LL intact'). When the same trout is treated with cobalt chloride to block the lateral line it no longer exhibits an escape response to a jet of water (B, gray bar, `LL blocked pre-experiment'). After the experiment, fish were retested to confirm that the cobalt chloride treatment did not wear off (C, `LL blocked post-experiment'). Scale bars, 1 cm. All values are mean ± s.e.m., N=4 fish.