Glands

• Glands:There is a large gland on each carapace valve, which are of taxonomic importance. In the subfamilies Archiconchoecinae and Halocypridinae these large glands are placed symmetrically on the posterior margin of the carapace. In the Conchoecinae, they are asymmetrical. On the right valve the usual position for the gland to open is at, or close to the posterior ventral 'corner'. In Conchoecilla it is placed just below the rostral incisure, and in Metaconchoecia species just ventral to the posterior dorsal corner. On the left valve the usual position for the gland is on the dorsal margin close to the posterior dorsal corner, but is often displaced anteriorly, notably in Metaconchoecia species in which it opens close to or even on the rostrum. 
  
  • Males glands: in males there is usually a group of glands on each valve that open just below the posterior dorsal corner, where the ends of the long terminal setae of the sixth pair of limbs project. There are numerous smaller glands arranged along the ventral margins of the valves that secrete mucus. 
    
  • Bioluminescence glands are often present on the lower edge of the incisure and also where the posterior margin is arched into an exhalent siphon. These glands release bioluminescence into the respiratory flow of water. This flow, driven by the beating of the epipodial appendages of the fifth and sixth limbs, enters the carapace below the rostrum, and is discharged through the exhalent siphon on the posterior margin. Species in which the rostrum is elongated into spines (e.g. Conchoecilla daphnoides) and/or there are large spines or tubercles at the posterior or ventral dorsal corners (e.g. Conchoecissa symmetrica) usually contain additional glands at the tips which generate bioluminescence, which is retained within the glands.

In males, there a corresponding asymmetry in some of the characteristics of the endopodite of the second antenna and the intromittent organ is a single appendage on the right side of the caudal furca. Note that in the myodocopids the intromittent organ is a paired appendage and there are no comparable asymmetries.