Furthermore, the ventral fin may exhibit some positive allometry because of the biomechanical demands of swimming [ 83], which would also be true for the dorsal fin and perhaps even the head crest as well (e.g., if it functioned as a rudder).
Pentecopterus lacks the cercal blades that occur in Megalograptus, where they have been interpreted as functioning as a biological rudder, like the pterygotid telson [ 67].
More experienced bodysurfers also use their trail arm as a rudder to steer across the wave.
Muskrats' large hind feet, fringed with stiff bristles and partially webbed, are used as oars when swimming, with the tail serving as a rudder.
When fishing, it swims underwater using its semi-extended wings as paddles to "fly" through the water and its feet as a rudder.
I do believe in knowing what you value most and using that as a rudder to guide your life.
Bennett also found that even in its capacity as a rudder, the crest would not provide nearly so much directional force as simply maneuvering the wings.
This structure is formed by the convergence of the dorsal and anal fins, and is used by the fish as a rudder.
Puffins have a special technique to swim underwater -- their wings move similar to when flying and their feet act as a rudder.
The mid-legs function as propelling oars and the rear-legs function as steering rudders.
