Martin G R, Brooke M de L
School of Biological Sciences, University of Birmingham, UK.
Brain Behav Evol. 1991;37(2):65-78. doi: 10.1159/000114347.
The Manx shearwater, Puffinus puffinus, is a pelagic sea bird which feeds from the surface of the sea and by shallow surface and plunge dives. Visits to breeding colonies are made at night. The mononuclear retinal field of the Manx shearwater eye is 148 degrees wide and is asymmetric with respect to the optic axis. The nasal and temporal hemi-fields equal 65 and 83 degrees, respectively. The binocular field is long and narrow, and the central placement of the bill suggests that vision is used to guide the bill position during foraging. A schematic model of the shearwater eye's optical system is presented, together with reanalysed data on the optical structure in the eye of the pigeon, Columba livia. The eyes of these two species are nearly identical in axial length and overall shape, but they are of quite different optical design. The shearwater eye has a shorter focal length and higher maximum image brightness, and the ratio of corneal:lens refractive power equals 0.4 and 1.6 in pigeon and shearwater eyes, respectively. In Manx shearwater eyes, the ratio of focal length:axial length and the ratio of lens refractive power:corneal refractive power may be correlated with a nocturnal life style. It is not clear whether the relatively low refractive power of the cornea is best regarded as a feature correlated with an amphibious life style or whether it is a consequence of adaptations for nocturnal activity.
马恩岛剪水鹱（Puffinus puffinus）是一种远洋海鸟，以海面、浅表层及俯冲潜水的方式觅食。它们在夜间前往繁殖地。马恩岛剪水鹱眼睛的单眼视网膜视野宽148度，相对于光轴不对称。鼻侧和颞侧半视野分别为65度和83度。双眼视野狭长，喙的中央位置表明视觉在觅食过程中用于引导喙的位置。本文给出了剪水鹱眼睛光学系统的示意图模型，以及对家鸽（Columba livia）眼睛光学结构重新分析的数据。这两个物种眼睛的眼轴长度和整体形状几乎相同，但光学设计却大不相同。剪水鹱眼睛的焦距较短，最大图像亮度较高，家鸽和剪水鹱眼睛中角膜与晶状体屈光力的比值分别为0.4和1.6。在马恩岛剪水鹱的眼睛中，焦距与眼轴长度的比值以及晶状体屈光力与角膜屈光力的比值可能与夜行性生活方式有关。目前尚不清楚角膜相对较低的屈光力究竟是与两栖生活方式相关的特征，还是适应夜间活动的结果。
