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ABSTRACT In the dark, expansive habitat of the deep sea, the production of light through bioluminescence is commonly used among a wide range of taxa. In decapod crustaceans, bioluminescence is only known in shrimps (Dendrobranchiata and Caridea) and may occur in different modes, including luminous secretions that are used to deter predators and/or from specialised light organs called photophores that function by providing camouflage against downwelling light. Photophores exhibit an extensive amount of morphological variation across decapod families: they may be internal (of hepatic origin) or embedded in surface tissues (dermal), and may possess an external lens, suggesting independent origins and multiple functions. Within Dendrobranchiata, we report bioluminescence in Sergestidae, Aristeidae, and Solenoceridae, and speculate that it may also be found in Acetidae, Luciferidae, Sicyonellidae, Benthesicymidae, and Penaeidae. Within Caridea, we report bioluminescence in Acanthephyridae, Oplophoridae, Pandalidae, and new observations for Pasiphaeidae. This comprehensive review includes historic taxonomic literature and recent studies investigating bioluminescence in all midwater and deep benthic shrimp families. Overall, we report known or suspected bioluminescence in 157 species across 12 families of decapod shrimps, increasing previous records of bioluminescent species by 65%. Mounting evidence from personal observations and the literature allow us to speculate the presence of light organs in several families thought to lack bioluminescence, making this phenomenon much more common than previously reported. We provide a detailed discussion of light organ morphology and function within each group and indicate future directions that will contribute to a better understanding of how deep‐sea decapods use the language of light. 

Abstract Farfantepenaeus duorarum (Burkenroad, 1939) is a commercially harvested decapod shrimp that ranges from the eastern coast of the United States, through the Gulf of Mexico, and as far south as Isla Mujeres, Mexico. We report for the first time the complete mitochondrial genome of F. duorarum. The mitochondrial genome is 15,971 base pairs in length and is comprised of 13 protein-coding genes (PCGs), 2 ribosomal RNA genes, and 22 transfer RNA genes. An intergenic space 982 bp in length located between the rrnS (12S) and trnI (Isoleucine) genes is presumed to be the D-loop. The mitochondrial gene order in F. duorarum is identical to that reported for congeners. To assess selection pressures within the mitochondrial genome, KA/KS ratios were calculated for all PCGs, and show values < 1, indicating that all genes are evolving under purifying selection. This work contributes one more mitochondrial genome to the penaeid shrimps, an economically targeted group.