Biology of Finfish and Shellfish

4.12.12. Mysis II

MTL: 3.50mm (3.39-3.58mm); MCL: 1.20mm (1.15-1.26mm).

Presence of a spine on scaphocerite and appearance of unsegmented pieopod buds distinguish this sub stage from mysisI; no change in spination of carapace and abdomen; cleft on telson extends to level of origin of penultimate pair of lateral telsonic setae.

A1 with increased number of setae on peduncle, inner flagellum has increased in length and outer flagellum which is longer than inner with 6 aesthaetes and 1 or 2 setae at distal end; A2 with a small ventral spine on outer distal end of 2nd segment of protopod, endopod nearly half length of exopod bearing a short apical seta, exopod with 19 long plumose setae along inner and distal margin and 1 spine at distal lateral angle; Md with small unsegmented palp, 8 free standing teeth on left and 3 on right Md; Mx1 without exopod, size of endopod reduced; Mx2 with 14 to 15 plumose setae on exopod; Mxp1 with 12 setae on exopod; Mxp2 with 5 segmented endopod, with newly added segment in middle without setae, terminal segment with 6 setae; Mxp3 with endopod longer than exopod, 3rd segment with 2 setae, a seta added to outer distal margin of 4th segment; PI P2 and P3 almost identical endopod 5 segmented, distal segment with 2 and penultimate segment with 3 long setae, endopod of P4 and P5 4 segmented, distal segment with 2 apical and 1 subapical setae, penultimate segment bears 2 setae; pleopods have a slight constriction in the middle indicating the beginning of segmentation; exopod and endopod of uropod with 18 setae. Duration of this sub stage was 24 to 48 hours.