Dj. Coughlin et al., CONTRACTION DYNAMICS AND POWER PRODUCTION OF PINK MUSCLE OF THE SCUP (STENOTOMUS CHRYSOPS), Journal of Experimental Biology, 199(12), 1996, pp. 2703-2712
Although the contribution of red muscle to sustained swimming in fish
has been studied in detail in recent years, the role of pink myotomal
muscle has not received attention. Pink myotomal muscle in the scup (S
tenotomus chrysops) lies just medial to red muscle, has the same longi
tudinal fibre orientation and is recruited along with the red muscle d
uring steady sustainable swimming. However, pink muscle has significan
tly faster rates of relaxation, and the maximum velocity of shortening
of pink muscle (7.26+/-0.18 muscle lengths s(-1), N=9, at 20 degrees
C, and 4.46+/-0.15 muscle lengths s(-1), N=6, at 10 degrees C; mean +/
- S.E.M.) is significantly faster than that of red muscle. These prope
rties facilitate higher mass-specific maximum oscillatory power produc
tion relative to that of red muscle at frequencies similar to the tail
beat frequency at maximum sustained swimming speeds in scup. Additiona
lly, pink muscle is found in anatomical positions in which red muscle
produces very little power during swimming: the anterior region of the
fish, which undergoes the lowest strain during swimming. Pink muscle
produces more oscillatory power than red muscle under low-strain condi
tions (+/-2-3 %) and this may allow pink muscle to supplement the rela
tively low power generated by red muscle in the anterior regions of sw
imming scup.