Precision of archerfish C-starts is fully temperature compensated.

Hunting archerfish precisely adapt their predictive C-starts to the initial movement of dislodged prey so that turn angle and initial speed are matched to the place and time of the later point of catch. The high accuracy and the known target point of the starts allow a sensitive straightforward assay of how temperature affects the underlying circuits. Furthermore, archerfish face rapid temperature fluctuations in their mangrove biotopes that could compromise performance. Here, we show that after a brief acclimation period the function of the C-starts was fully maintained over a range of operating temperatures: (i) full responsiveness was maintained at all temperatures, (ii) at all temperatures the fish selected accurate turns and were able to do so over the full angular range, (iii) at all temperatures speed attained immediately after the end of the C-start was matched - with equal accuracy - to 'virtual speed', i.e. the ratio of remaining distance to the future landing point and remaining time. While precision was fully temperature compensated, C-start latency was not and increased by about 4 ms per 1°C cooling. Also, kinematic aspects of the C-start were only partly temperature compensated. Above 26°C, the duration of the two major phases of the C-start were temperature compensated. At lower temperatures, however, durations increased similar to latency. Given the accessibility of the underlying networks, the archerfish predictive start should be an excellent model to assay the degree of plasticity and functional stability of C-start motor patterns.