Hadden Peter W, Zhang Jie
Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
Vision (Basel). 2023 Jan 17;7(1):6. doi: 10.3390/vision7010006.
Penguins require vision that is adequate for both subaerial and submarine environments under a wide range of illumination. Here we provide a structured overview of what is known about their visual system with an emphasis on how and how well they achieve these goals. Amphibious vision is facilitated by a relatively flat cornea, the power in air varying from 10.2 dioptres (D) to 41.3 D depending on the species, and there is good evidence for emmetropia both above and below water. All penguins are trichromats with loss of rhodopsin 2, a nocturnal feature, but only deeper diving penguins have been noted to have pale oil droplets and a preponderance of rods. Conversely, the diurnal, shallow-diving little penguin has a higher ganglion cell density (28,867 cells/mm) and f-number (3.5) than those that operate in dimmer light. In most species studied, there is some binocular overlap, but this reduces upon submergence. However, gaps in our knowledge remain, particularly with regard to the mechanism of accommodation, spectral transmission, behavioural measurements of visual function in low light, and neural adaptations to low light. The rarer species also deserve more attention.
企鹅需要在广泛的光照条件下，具备适用于陆地和水下环境的视觉能力。在此，我们对其视觉系统的已知信息进行了结构化概述，重点关注它们如何以及在多大程度上实现这些目标。相对扁平的角膜有助于两栖视觉，根据物种不同，空气中的屈光度从10.2屈光度（D）到41.3 D不等，并且有充分证据表明企鹅在水上和水下均为正视眼。所有企鹅都是三色视者，视紫红质2缺失，这是一种夜间特征，但只有潜水更深的企鹅被注意到有浅色油滴和大量视杆细胞。相反，日行性、浅潜的小企鹅比在较暗光线下活动的企鹅具有更高的神经节细胞密度（28,867个细胞/mm）和f值（3.5）。在大多数研究的物种中，存在一定程度的双眼重叠，但在潜水时会减少。然而，我们在知识方面仍存在空白，特别是在调节机制、光谱透射、低光下视觉功能的行为测量以及对低光的神经适应方面。较为稀有的物种也值得更多关注。
