343 © Springer Nature Switzerland AG 2020 A. Singh, M. Kango-Singh (eds.), Molecular Genetics of Axial Patterning, Growth and Disease in Drosophila Eye, https://doi.org/10.1007/978-3-030-42246-2_12 Eye for an Eye: A Comparative Account on Compound Eye of Drosophila melanogaster with Vertebrate Eye Arushi Rai, Sonia Narwal, Harsh Kanodia, and Meghana Tare Introduction Eyes, as mentioned by philosopher William Paley, are “miracle of design.” Eyes are indeed amazing organs in the animal kingdom, for their ability to provide a unique sense that makes most of the animals stand apart from rest of the living organisms. Although not all kingdoms of life are devoid of visual senses, the ability to connect sense of vision to that of complex nervous system for processing and image forma- tion is unique to the animal kingdom. Diversity of the eyes in the animal kingdom has been attributed to evolution over a large period of time. Based on evidences from fossil records, frst eyes appear some 540 million years ago (Parker 2009). There are different kinds of eyes animals possess, which work in different fashions, in order to “sense” the objects, and may be to form an image. Of all diverse life forms, eye of Drosophila melanogaster is an example of eyes; for an eye; for, it has compound eyes, for sensing, processing and forming the image. For over a century now, Drosophila melanogaster eye has provided a new dimension to several differ- ent aspects of understanding in the felds of development and several different dis- eases (Borst 2009). Santiago Ramon y Cajal, a neuroanatomist was the frst to notice the similarities between the visual system of vertebrates and that of the insects. He documented a striking similarity between the neuronal circuits that form the major framework of visual system in fies and vertebrates (Cajal and Sanchez 1915). Compound eyes are built as convex structures around the outside of an animal’s head, and even though their arrangement looks similar to vertebrate eyes (both sides of head), they are fundamentally different from the concave structure of single chamber eyes (Fig. 1). In spite of this major topological difference, however, the A. Rai · S. Narwal · H. Kanodia · M. Tare (*) Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Pilani, Rajasthan, India e-mail: meghana.tare@pilani-bits.pilani.ac.in