Table 1.

Mean (±s.d.) relative mass of each extraocular muscle (muscle mass as percentage of total eye mass) in the opah, Lampris guttatus (N=7) and the chub mackerel, Scomber japonicus (N=5)

Extraocular muscleLampris guttatus (%)Scomber japonicus (%)
Lateral rectus11.70±1.044.81±0.83
Superior rectus4.33±0.581.64±0.49
Inferior rectus4.27±0.661.51±0.55
Medial rectus10.27±0.982.68±0.68
Superior oblique4.56±0.621.56±0.22
Inferior oblique4.92±0.281.70±0.71
  • In both species, the lateral rectus muscle is significantly larger than all other extraocular muscles (ANOVA, P<0.05) and the medial rectus is significantly larger than the other four extraocular muscles (ANOVA, P<0.05). The mean relative mass of each extraocular muscle is significantly greater in opah than in chub mackerel (two-sample t-test, P<0.05)