Graphics Reference
In-Depth Information
(a)
FIG 4.71
a: The perch has a large
centrally placed dorsal fin that gives
it great maneuvrability. b: The pike
has a dorsal fin located much further
back in the body, providing additional
thrust for higher speeds.
(b)
The Dorsal Fin
The dorsal in is located on the back of the fish and varies in number from
one to three. These fins also vary a great deal in size and shape. Dorsal fins
are mostly used to assist in maneuverability and in the prevention of a rolling
action, but some of them incorporate sharp spines that not only aid rigidity,
they afford some protection against predation. In most fish the dorsal in does
not contribute directly to providing power for locomotion, though in seahorses
the dorsal fin provides the main propulsion through its undulating action.
FIG 4.72
Dorsal fins.
The Caudal Fin
The caudal fin is most commonly known as the tail and is attached to the
body by the caudal peduncle, through which the power for locomotion is
provided to the tail. Though other fins make a contribution to powering
locomotion, it is through the caudal fin that the power for high speed and
sustained swimming are transmitted.
