The digestive tract of vertebrates is a specialized organ system that digests food, absorbs nutrients, and expels waste products. In general, organ order and function of the gastrointestinal tract has remained consistent across vertebrate evolution. However, organisms such as the parasitic lamprey that have no stomach, or Xenopus which has relatively short intestines for a terrestrial mammal, have led researchers to investigate the environmental pressures that lead to the evolution of certain organ structures. My research focuses on how similar patterning genes in primitive organisms such as Leucoraja erinacea and more advanced terrestrial vertebrates such as chick and mouse, have led to morphologically different digestive tracts. In L. erinacea, the small intestine forms a spiral valve whose length is shorter and utilizes its curved structure to maximize the absorptive surface area to volume ratio as compared to the terrestrial small intestines which are longer and packed to function in a similar manner. In order to investigate this question, I utilize whole mount RNA in situ hybridization to compare the expression patterns of known GI patterning genes (Cdx2, Hoxd12, Wnt5-a, and Shh) in distantly related lineages at similar embryonic stages. Our results revealed that Cdx2, Hoxd12, and Shh displayed similar expression patterns across species, while Wnt5-a was expressed in the posterior region of the spiral valve as compared to the mouse small instestine, in which Wnt5-a was expressed across the entire mid-gut. These expression patterns allow us to develop a better understanding of how genes can function differently in organisms to create distinctive organ morphologies, such as the skate spiral valve versus long coiled intestines of other vertebrates. In future studies, similar approaches can be utilized in other model systems to examine how organ structures have evolved in different points of evolutionary time.