Miyashita et al.: Morphological development and growth of Thunnus thynnus 
607 
Table 2 
recorded for the myomere on which it occurs, n indicates the number of specimens examined at each size range. 
Myomere 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
31 
32 
33 
34 
35 
36 
37 
38 
39 
n 
29 
29 
7 
7 
7 
7 
14 
14 
21 
21 
36 
43 
14 
14 
7 
14 
14 
7 
22 
7 
7 
19 
15 
4 
11 
19 
4 
19 
19 
33 
30 
26 
30 
15 
19 
27 
7 
11 
4 
4 
4 
7 
11 
7 
11 
15 
4 
11 
15 
19 
15 
19 
22 
7 
7 
21 
8 
8 
17 
25 
8 
17 
8 
17 
8 
8 
8 
17 
17 
17 
25 
25 
8 
12 
10 
10 
10 
10 
10 
30 
10 
20 
10 
10 
10 
20 
10 
20 
20 
30 
10 
20 
10 
10 
50 
40 
50 
10 
10 
10 
10 
22 
11 
6 
6 
6 
6 
6 
11 
6 
22 
22 
6 
11 
22 
6 
18 
10 
10 
10 
20 
10 
20 
10 
30 
70 
30 
20 
10 
20 
20 
20 
10 
20 
10 
20 
0 
10 
30 
20 
20 
10 
30 
40 
10 
40 
10 
10 
54 
38 
38 
31 
23 
38 
31 
23 
23 
15 
31 
8 
31 
15 
23 
8 
15 
15 
8 
38 
13 
92 
77 
77 
77 
69 
69 
69 
69 
69 
62 
54 
69 
69 
69 
54 
54 
62 
46 
38 
23 
13 
83 
67 
58 
75 
58 
83 
58 
58 
67 
58 
75 
50 
50 
33 
33 
25 
58 
67 
33 
17 
12 
100 
80 
70 
90 
70 
100 
70 
70 
80 
70 
90 
60 
60 
40 
40 
30 
70 
80 
40 
20 
10 
Table 3 
is recorded for the myomere on which it occurs, n indicates the number of specimens examined at each size range. Melanophores were 
Myomere 
23 
24 
25 
26 
27 
28 
29 
30 
31 
32 
33 
34 
35 
36 
37 
38 
39 
n 
29 
14 
7 
57 
7 
64 
29 
14 
21 
79 
50 
36 
57 
50 
36 
43 
36 
14 
15 
15 
37 
11 
26 
37 
41 
41 
30 
44 
44 
26 
26 
48 
30 
33 
52 
27 
19 
33 
29 
29 
24 
43 
38 
38 
52 
24 
57 
43 
43 
19 
33 
29 
57 
21 
17 
8 
33 
17 
17 
42 
42 
17 
25 
83 
50 
50 
50 
33 
58 
33 
25 
12 
20 
30 
40 
60 
10 
10 
60 
60 
40 
70 
60 
60 
30 
20 
30 
20 
20 
10 
30 
10 
20 
60 
30 
30 
10 
30 
30 
40 
50 
20 
0 
10 
30 
20 
0 
10 
6 
11 
22 
28 
39 
39 
33 
56 
28 
44 
28 
28 
22 
50 
22 
17 
39 
18 
10 
30 
50 
20 
50 
60 
60 
40 
60 
80 
50 
40 
60 
30 
30 
30 
10 
10 
10 
20 
30 
20 
40 
40 
50 
50 
50 
90 
70 
60 
50 
70 
40 
60 
10 
8 
15 
15 
23 
54 
46 
62 
54 
69 
62 
62 
54 
62 
46 
46 
13 
8 
15 
8 
23 
31 
54 
46 
62 
46 
85 
77 
54 
77 
77 
85 
31 
13 
8 
25 
33 
42 
58 
33 
58 
67 
67 
67 
75 
50 
42 
12 
10 
40 
40 
40 
60 
70 
80 
70 
70 
70 
70 
60 
40 
10 
and G). The number of anterior and posterior preopercular 
spines decreased at 17 nun BL. At >19.23 mm BL, no ante- 
rior preopercular spines were observed, except in one spec- 
imen (24.00 mm BL) that had two anterior preopercular 
spines. Juveniles had three posttemporal spines when these 
spines were fully developed. The largest specimen with a 
posttemporal spine was 24.23 mm BL, and the largest spec- 
imen examined, 37.78 mm BL, had no spines on its head. 
Teeth and squamation 
Upper and lower jaw teeth were first observed at 5.35 and 6.32 
mm BL, respectively. Palatine teeth appeared at 7.20 mm BL 
and most specimens >9 mm BL had fully developed palatine 
teeth. At >18.00 mm BL, specimens did not have these teeth. 
Squamation was incomplete in the size range examined 
in this study. The smallest scaled specimen (27.37 mm BL) 
