Shellfish Breeding and Hatchery Management (2+1)

8.1.3 Secondary sexual characters of prawns (M.rosenbergii)

Male :

• Second pair of swimmerets are modified to form spinous projection known as appendix masulina, which helps in copulation
• Genital pores are found at the base of 5^th walking legs.
• The endopodite of 2^nd pleopod has appendix interna alongwith appendix masculina.
• Reproductive setae are absent on the ventral side of the thorax and pleopods of mature male.
• Ventral side of the first abdominal segment has a hard lump at the centre, which can be felt with finger.

Female :

• First 5 pairs of softer swimmrets are the attachment sites for cluster of eggs within the brood chamber.
• Genital pores at base of 3^rd walking legs.
• Extended pleura of 1^st, 2^nd and 3^rd tail segments to form brood chamber to carry eggs after spawning, fertilization and before hatching.
• Reproductive (ovipositing and ovigerous) setae on the ventral side of thorax and pleopods of mature females.
• Ovipositing setae appear on the coxa of last 3^rd pair of pereopods and posterior margin of sperm receptacle area and the pleopods. It helps in guiding and propelling eggs during spawning.
• Ovigerous setae serve to anchor the eggs to pleopods.
• Ovaries can be seen as large orange-coloured mass occupying a large portion of dorsal and lateral cephalothorax in a ripe or ovigerous female.