Biology of Finfish and Shellfish (2+1)

4.12.9. Protozoea II

MTL: 1.52 mm (1.40-1.55 mm); MCL: 0.74 mm (0.71-0.76 mm).

Presence of a well developed curved rostrum, bifurcated supraorbital spines, stalked compound eyes and absence of frontal organs distinguish this sub stage from the previous one.

A1 with distal segment bearing 4 aesthaetes and 2 long setae; Md asymmetrical, right and left Md with 1 and 5 free standing teeth between incisor and molar processes; Mx1 with 8 setae on distal lobe of protopod; Mxp1 with 2 plumose setae on 2nd segment of endopod.

As in the previous stage, the larvae show increase in length towards end of this stage. There is a definite increase in body length, MTL being 1.88 mm (1.72-1.99 mm) and MCL: 0 83 mm (0.78-0 84 mm). Advanced stage of protozoea II can be easily distinguished from the early stage by the presence of developing buds of five pereopods and Mxp3 and by the increase in length of abdominal segments. Moreover, the developing uropods can be clearly seen inside the lobes of caudal furca. Duration of this sub stage was 48 to 72 hours.