Marine crustaceans present an extremely interesting set of examples in which to examine visual development and metamorphosis. Larvae of these animals are almost always planktonic, living in the light field of open waters. The presence of a simple, predictable photic environment, the relatively basic visual requirements of larvae, and the need to remain transparent to reduce predation lead to the use of a single eye type throughout all marine crustacean larvae. Adult crustaceans, on the other hand, use a greater diversity of optical designs than all other animals combined, occupy habitats from the deep sea to mountaintops, and have very complex visual systems and behaviors. Thus, visual development varies tremendously among modern Crustacea. In this brief review, we consider the structure and development of marine crustacean eyes, focusing on optics, retinal design, and metamorphosis of the visual pigments.