Shellfish Breeding and Hatchery Management (2+1)

Characteristic features of early postlarvae of Penaeus spp.

Objective : To familiarize with the identification characters of early postlarvae of  Penaeid shrimps

Procedure

Follow the points given below to identify the postlarval stages of shrimps.

• Postlarvae I of P.indicus, P.monodon, P.semisulcatus are more or less morphologically similar. Following characters can be easily observed .
• Long and slender body with total length of 7-13 mm.
• Absence of antennal spine on carapace; rostrum reaching end of eye and with 4-6 dorsal spines. Supraorbital and hepatic spines present on carapace; telson with 8 pairs of setae.

First post larval stage (PL1) :

• Superficially resembles 3^rd mysis except for the development of setae on the pleopods.
• First 3 walking legs lose the swimming setae and their claws become functional.

XII Post Larvae:

• Teeth on upper and lower margin of rostrum.
• Behavioral changes in swimming.
• Body transparent with slightly brown coloured.
• Chromatophores on the head.

Significance:

Identification of different postlarval stages is of much importance in  postlarval production and management.