Our work addresses evolutionary questions that have been historically difficult to dissect and will generate a much-needed animal model for human degenerative eye diseases. Establish a timeframe for embryonic eye development, specifically when the morphological differences in eye development in surface and cave populations of Asellus aquaticus occur.The morphological differences between surface and cave animals are established during embryonic development. Specifically, eye development begins in cave embryos similar to eye development in the surface population and then degenerates ultimately leading to the absence of eyes.The first objective is to determine whether morphological differences between cave and surface animals are established embryonically or post-embryonically. In particular, the focus is on when and how the cave and surface forms diverge in eye development. It is expected that these experiments will generate an understanding of the time frame of both surface and cave embryonic development and a foundational basis for further genetic and developmental