Graphics Reference
In-Depth Information
FIG 4.85 The stride length of a fish
swimming by undulation.
Swimming with a Rowing Action
Occasionally fish swimming at very slow speeds choose to propel themselves
forward with the use of their pectoral fins rather than using their entire body
to propel the caudal fin. Using their pectoral fins as oars, they are capable of
creating a rowing type of action.
During this kind of action the fins or limbs of the animal may act as an oar,
with the surface of the limb or fin moving more or less at a right angle to the
body, creating thrust on the power stroke. On the return stroke the fin or limb
moves at a far shallower angle of attack, thereby reducing drag. The power
stroke of the rowing action is generally a more rapid action than the animal's
swimming speed. Human swimming uses this kind of drag action on the
arms because they are used as either horizontally or vertically oriented oars.
Propulsion by some species of water beetles is more akin to the rowing action
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