Fig. 3. Time course of pigment movement (expansion and retraction) during the day in both species of toadfish. (A) Pigment movement across the whole cornea and (B) within the pupil zone, and (C,D) a comparison of pigment movement in the ventral and dorsal hemifields of the whole cornea. (A) Corneal pigment cover varies from 53% during dark-adaptation (broken lines) to 100% during light-adaptation (solid lines) in T. hamiltoni and from 40% to 80%, respectively, in T. pleurogramma. (B) During light-adaptation (solid lines) the entire pupil zone is 100% pigmented, but is free of pigment after dark-adaptation (broken lines). (C,D) Pigment movement is symmetrical in the ventral (V) and dorsal (D) corneal hemifields of both species. The time course of the pigment movement is similar in both species during pigment expansion (C) while there are differences during pigment retraction (D). In T. pleurogramma the pigment retracts at a slow constant rate, whereas in T. hamiltoni it retracts in two phases, quickly between 10–20 min and slowly between 20–60 min.

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