title: Rod-cone based color vision in seals under photopic conditions.
abstract: Marine mammals have lost the ability to express S-cone opsin, and possess only one type of M/L-cone in addition to numerous rods. As they are cone monochromats they should be color blind. However, early behavioral experiments with fur seals and sea lions indicated discrimination ability between many shades of grey and blue or green. On the other hand, most recent training experiments with harbor seals under "mesopic" conditions demonstrated rod based color blindness (Scholtyssek et al., 2015). In our experiments we trained two harbor seals (Phoca vitulina) and two South African fur seals (Arctocephalus pusillus) with surface colors under photopic conditions. The seals had to detect a triangle on grey background shown on one of three test fields while the other two test fields were homogeneously grey. In a first series of experiments we determined brightness detection. We found a luminance contrast of >3% sufficient for correctly choosing the triangle. In the tests for color vision the triangle was blue, green or yellow in grey surround. The results show that the animals could see the colored triangle despite minimal or zero brightness contrast. Thus, seals have color vision based on the contribution of cones and rods even in bright daylight.
authors.affiliation: Institut für Zoologie III (Neurobiologie), Johannes Gutenberg-Universität, 55099 Mainz, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Oppermann
authors.affiliation: Institut für Zoologie III (Neurobiologie), Johannes Gutenberg-Universität, 55099 Mainz, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Schramme
authors.affiliation: Institut für Zoologie III (Neurobiologie), Johannes Gutenberg-Universität, 55099 Mainz, Germany. Electronic address: neumeyer@uni-mainz.de.
authors.forename: Christa
authors.initials: C
authors.lastname: Neumeyer
mesh_terms: D000818:Animals; D055253:Color Vision / Q000502:physiology*; D015350:Contrast Sensitivity / Q000502:physiology; D005260:Female; D046069:Fur Seals / Q000502:physiology*; D008297:Male; D046049:Phoca / Q000502:physiology*; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology*; D012684:Sensory Thresholds
keywords: Color vision; Cones; Harbor seal (Phoca vitulina); Rods; South African fur seal (Arctocephalus pusillus)