Throughout their evolutionary history, organisms have evolved a myriad of novel complex traits, increasing survival and reproductive success. However, the evolutionary history of these novel traits is often difficult to document. To understand the genetic origins of novel complex traits, we use a gene co-expression network-based approach to identify genes responsible for the origin of a novel trait – bioluminescence in Cypridinid ostracods. Sea fireflies emit light-producing compounds from a light organ and use bioluminescence for both anti-predator defense and courtship signals. The light reaction involves a substrate, luciferin, and an enzyme, luciferase, each of which is synthesized in separate gland cells and discharged in a mucous-like substance. Here, we aim to identify gene candidates responsible for the synthesis of luciferin, a molecule with a fundamental and defined functional role in light production behaviors. We hypothesize that genes involved in the luciferin biochemical pathway and production of secreted mucus are co-regulated with luciferase in response to specific stimuli, such as defense or courtship signaling. We generated transcriptomic profiles of the bioluminescent ostracod, Vargula tsujii, under various physiological and environmental conditions. 53,409 genes were selected for weighted gene co-expression analysis and highly co-expressed genes were divided into 100 modules. In the co-expression module containing luciferase, we identified genes that encode mucous-like proteins with VWD domains and venom-like cysteine-rich proteins and endopeptidases. Future work will add expression data from multiple bioluminescent ostracods to facilitate the identification of candidate genes in the luciferin biochemical pathway.