Meeting Abstract
Mudskippers are a charismatic assemblage of gobiid teleosts with extended phases of activity on land. Their amphibious lifestyle is considered to be coupled to a range of peculiar morphological features found in all major functional systems, including their visual system. For example, the eyes of mudskippers are placed far up dorsally in the head in comparison to other gobies, and common wisdom holds that mudskippers have large panoramic field of views. We tested this hypothesis with the ophthalmic reflex technique and quantified the static visual fields of the African mudskipper (Periophthalmus barbarus) and two related gobiids, the ornate rainbow goby (Stiphodon ornatus) and the flaming arrow goby (Sicyopus zosterophorus). Surprisingly, our results demonstrate that the static panoramic field of view of the African mudskipper is smaller (maximum extent ca. 290 deg) than the panoramic fields of the two related gobies (ca. 315 deg). However, the reduced panoramic field of the African mudskipper is traded for a region of binocular overlap that, while similar in terms of its maximum width, is nearly twice as long along the dorsal hemisphere. This pattern of reduced panoramic but enlarged binocular field in the African mudskipper holds true for visual field measurements in both air and water. Regions of binocular overlap are considered to improve visual performance, and we propose that the elongated binocular field of view seen in the African mudskipper may represent a selective advantage tied to their intertidal habitat at the water-air interface.
