Graphics Reference
In-Depth Information
the anal fin. These fins are also used to stabilize the fish during swimming,
preventing roll and allowing a high degree of control, enabling slight
movements and delicate maneuverability.
The Anal Fin
The anal fin is located on the underside of the fish, just behind the vent or
anus, and is used to prevent roll and thereby ensures stability while the fish
is swimming forward. Fish will often furl their fins, reducing their profile and
allowing for a more streamlined shape, thereby reducing drag and increasing
speed—a very useful tactic when acceleration over short distances is required.
FIG 4.77
Anal fins provide the fish
with stability and aid maneuverability.
The Adipose Fin
A number of fish possess a small fleshy fin located on the back behind the
dorsal in and in front of the caudal in. The adipose in is absent in most
fish, though all salmonids, trout, salmon, grayling, and char have them.
The purpose of this fin is uncertain since it has no rays and doesn't seem to
provide or assist in either maneuverability or locomotion.
FIG 4.78
The adipose fin is a small,
fleshy fin located behind the dorsal fin.
Some species of fish possess
finlets
, which are rows of small, rigid fins located
on the upper and lower sides of the fish along the caudal peduncle, between
the dorsal and anal fins and the caudal fin. These finlets are hard and not
retractable.
Not all fish have the same kind of scales. Some are covered in very large
numbers of small scales; others have smaller numbers of large scales. There
