Biology of Finfish and Shellfish (2+1)

4.12.14. Postlarva I

MTL: 5.03 mm (4.55 - 5.26 mm); MCL: 1.53 mm (1.44- 1.61 mm).

Rostrum with 1 or 2 dorsal spines, supraorbital, hepatic and pterygostomial spines present, the latter often very small, median dorsal spines usually present on 4th, 5th and 6th abdominal segments, lateral spines present on 5th and 6th abdoming segments, anal spine still present on i6th abdominal segment, exopods of P small and without setae, pleopods well developed and setose, telson rectangular in shape carrying 3 pairs of lateral and 5 pairs of terminal setae' median notch practically absent.

Al with statocyst at base of 1^st segment, well developed ventromedian spine still present on basal segment; inner branch of distal segment 3 segmented, longer than outer and carries 4 setae apically, of which 1 is as long as the branch, outer branch 2 segmented carrying 8 aesthaetes and 3 setae; A2 with endopod 6 segmented, distal segment apically bearing 3 long and 3 short setae; exopod with 27 setae and one anterolateral spine; Md has become almost symmetrical, free standing teeth lost, palp well developed and 2 segmented, carrying setae; Mx1 with endopod much reduced, unsegmented and without setae; distal lobe of protopod larger than proximal, distal and proximal lobes with 13 to 18 and 7 to 8 setae respectively; Mx2 with much reduced protopod having 4 endites, proximal 2 endites with 2 setae, distal 2 endites carry 5 to 6 bristle like setae, endopod reduced, unsegmented, without setae, scaphognathite very conspicuous bearing 29 to 30 plumose setae; Mxp1 with endopod and exopod reduced in size without segments and setae, protopod has become wide with numerous setae, epipod well developed; Mxp2 with exopod vestigial, endopod recurved, distal segment with 6 spine-like setae, penultimate segment naked, protopod carries a gill; Mxp3 with gill on protopod, exopod rudimentary without setae, 4th segment of endopod with 5 setae; PI with rudimentary gill on protopod, exopod much reduced, without setae, chelae fully developed; P2 and P3 progressively longer than PI; P4 and P5 almost similar, exopod reduced, endopod 5 segmented, 3rd and 4^th segments carry 3 setae each; 26 to 27 setae on margin of exopod and endopod of uropod. Duration of this sub stage was 24 to 30 hours.