The presence of a long-wavelength sensitive (LWS) opsin gene was  demonstrated in the stygobitic crustacean Creaseria morleyi (Creaser,  1936) by PCR readings from genomic DNA. In order to find the expression  of this gene in extraocular tissue, shrimps were collected and placed in a  tank to expose them to light/dark conditions for a period of 72 hours, and  immediately after, sacrificed and sampled for RNA in the eyes, cephalothorax,  abdomen, and sixth abdominal segment plus uropods. The transcripts of  the LWS opsin gene were found in the eyes and abdomen of individuals  exposed to light. The expression of these opsins could be involved in  extravisual functions such as synchronization of their biological processes  with environmental cycles related to diurnal vertical migration.