Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
Centre for Organismal Studies, University of Heidelberg, 69120, Heidelberg, Germany.
Anim Cogn. 2023 Nov;26(6):1817-1835. doi: 10.1007/s10071-023-01818-6. Epub 2023 Aug 31.
Light provides a widely abundant energy source and valuable sensory cue in nature. Most animals exposed to light have photoreceptor cells and in addition to eyes, there are many extraocular strategies for light sensing. Here, we review how these simpler forms of detecting light can mediate rapid behavioural responses in animals. Examples of these behaviours include photophobic (light avoidance) or scotophobic (shadow) responses, photokinesis, phototaxis and wavelength discrimination. We review the cells and response mechanisms in these forms of elementary light detection, focusing on aquatic invertebrates with some protist and terrestrial examples to illustrate the general principles. Light cues can be used very efficiently by these simple photosensitive systems to effectively guide animal behaviours without investment in complex and energetically expensive visual structures.
光是一种广泛存在的能源，也是自然界中非常有价值的感觉线索。大多数接触到光的动物都有光感受器细胞，除了眼睛之外，还有许多用于感知光的眼外策略。在这里，我们回顾了这些更简单的光检测形式如何介导动物的快速行为反应。这些行为包括避光（light avoidance）或避光（shadow）反应、趋光性、向光性和波长辨别。我们回顾了这些基本光检测形式中的细胞和反应机制，重点介绍了水生无脊椎动物，以及一些原生动物和陆地动物的例子，以说明一般原理。这些简单的感光系统可以非常有效地利用光线索，有效地引导动物行为，而无需投资于复杂且能量昂贵的视觉结构。
