Cs. Wardle et al., TUNING IN TO FISH SWIMMING WAVES - BODY FORM, SWIMMING MODE AND MUSCLE FUNCTION, Journal of Experimental Biology, 198(8), 1995, pp. 1629-1636
Most fish species swim with lateral body undulations running from head
to tail, These waves run more slowly than the waves of muscle activat
ion causing them, reflecting the effect of the interaction between the
fish's body and the reactive forces from the water, The coupling betw
een both waves depends on the lateral body shape and on the mechanical
properties of the tail. During steady swimming, the length of each my
otomal muscle fibre varies cyclically. The phase relationship between
the strain (muscle length change) cycle and the active period (when fo
rce is generated) determines the work output of the muscle. The muscle
power is converted to thrust either directly by the bending body or a
lmost exclusively by the tail, depending upon the body shape of the sp
ecies and the swimming kinematics. We have compared the kinematics and
muscle activity patterns from seven species of fish with different bo
dy forms and swimming modes and propose a model which yields a consist
ent pattern, with at least three extremes. Subtle tuning of the phase
relationship between muscle strain and activation cycles can lead to m
ajor changes in the way muscles function in different swimming modes.