Shellfish Breeding and Hatchery Management (2+1)

8.1.2 Secondary sexual characters of shrimps (Penaues spp.)

Male :

• Modified abdominal appendages (1^st and 2^nd pairs) and abdominal segments (the petasma and appendix masculina) that deliver sperm to the female’s sperm receptacle (the thelycum). The petasma and appendix masculina are located on the ventral surface.
• The petasma is formed by the fusion of the endopodites of the first pair of pleopods which are modified as interlocking structures for spermatophore transfer.
• The appendix masculina are on the endopodites of the second pair of pleopods and serve to open the petasma.
• The gonopore is located at the base of 5^th walking leg.

Female :

• A thelycum is present in the thoracic sterna between peropods IV and V. It is meant for storing the spermatophore.
• Thelycum consists of a median plate and 2 lateral plates which enclose a seminal receptacle for storing spermatophores.
• Female gonopore is located at the base of 3^rd walking legs.