All larvae have 26 myomeres
(6-8 preanal myomeres
during the preflexion stage, shifting to 10-11 during the postflexion stage).
Species Trunk myomeres
Circumoral teeth American Brook Lamprey 64-75 Unicuspid Northern Brook Lamprey 47-56 Unicuspid Silver Lamprey 47-55 Unicuspid Chestnut Lamprey 49-56 Bicuspid Species Dorsal fin Lateral line pores American Brook Lamprey Separate None Northern Brook Lamprey Connected None Silver Lamprey Connected Black Chestnut Lamprey Connected Black Table 2.
9 II 9 7 Adults II-III 8-10 7 Caudal-fin rays Body length Total range (mm) myomeres
Vertebrae Upper Lower 2.
lineatus since in this sample there is a group of melanophores between myomere
9 to 13 as the main characteristic, and for Diapturus peruvianus because of the three spots displayed in the dorsal margin of the intestines from the insertion of the pectoral fin to the anus (Jimenez et al.
Although all young gills are colocalized with myomeres
, the mouth and gill pores develop in the unsegmented ventral wall--that is, ventral to the left oral hood or the metapleural fold.
Larvae of northern sculpin have 35-36 myomeres
, pelvic fins with one spine and two rays, a bony preopercular shelf, four preopercular spines, 3-14 irregular postanal ventral melanophores, few, if any, melanophores ventrally on the gut, and in larger specimens, two rows of ctenoid scales directly beneath the dorsal fins extending onto the caudal peduncle.
During days 17-21, the optic capsule and eye lenses formed, the head and anterior body became thick and more defined, and the notochord, myomeres
, and Kupffer's vesicle became visible (Table 1).
3, A and B) showed a distinct pattern of 12 to 23 small postanal melanophores serially arranged, about one per myomere
, along the ventral midline.
Because of the difficulty in accurately counting myomeres
in transforming clupeids (Hettler, 1984; Ditty et al.
pauciradiatus can be identified by using myomere
counts (56-58 vs.
These are distinguishable from hemiramphid larvae by their higher myomere
count (62-70), greater number of principal caudal-fin rays (16-17), presence of dorsal and anal finlets, and much heavier pigmentation (Bruce and Sutton, 1998; Trnski et al.
Each melanophore is recorded for the myomere
on which it occurs, n indicates the number of specimens examined at each size range.