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Figure 3—figure supplement 3. (a) Five dpf and six dpf larvae were embedded in agarose with their eyes cut free and placed under a microscope. Using an additional mirror, we recorded simultaneous image time series along both the dorsoventral and mediolateral axes. Vertical eye position was determined geometrically for each individual frame (see Materials and methods). Because some larvae were embedded in such a way that mediolateral axis was not entirely aligned with the true horizon of the environment, we measured vertical eye position (b) relative to both the true environmental horizon, and (c) the mediolateral body axis, and in both cases, compared the left (L) and right eyes (R) of larvae embedded upside-up (uu) or upside-down (ud). To facilitate comparison, positive signs were chosen to roughly correspond to the dorsal hemisphere in both cases. Bars indicate mean after pooling across all frames, error bars show corresponding standard error of the mean (s.e.m.). In summary, larval eyes were almost always inclined towards the dorsum, irrespective of the direction of embedding. The fish do not appear to compensate for their orientation with respect to the gravitational axis.