Time: 12:00PM–1:30PM

How can a simple eye provide spatial information about the animal's environment? Of the five simple eye types I've found in the tiny worms of the phylum Nematoda, only two have optics that can focus light and none have a retina. Yet they can navigate towards light or dark areas in their field of view. I will first describe the unique way that spatial discrimination is accomplished by one species. Then I will examine the variety of eye structures and how their components could have evolved. My observations have raised questions as to what is the minimum that we can call an eye or vision.