Fig. 3. The effect of applying horizontal and vertical spatial filters to representative images of a cuttlefish camouflaged perpendicular and parallel to the sand and gravel backgrounds (Fig. 1). Fine background (sand) - the horizontal filter (A) found no horizontal structure in the cuttlefish camouflage pattern (B) and the vertical filter (C) found no vertical structure in the cuttlefish camouflage pattern (D). For the medium background (gravel) - the horizontal filter (E) found no horizontal structure in cuttlefish camouflage pattern (F) and the vertical filter (G) found no vertical structure in cuttlefish camouflage pattern (H). This analysis was run for a range of filter widths; the images shown are those where the filtered scale most closely matched the width of background stripe, and so one might expect an effect of orientation on the pattern.