Fish Anatomy - Fins And Tail
The fins and tail of fish provide a method of propulsion and stability they are also used for defence in some fish ( lionfish ). In some cases as a spawning aid, during pre-spawning and courtship displays, egg and fry care aids. Fins and the tail are cartilage or bone webbed with tissue that can be either soft or hard or erect and are controlled by small muscles that have the ability to extend or fold the fins. There are generally seven fins in total. There is three single fins, the caudal fin (tail), dorsal fin (the back) and anal fin (under the back of fish near the tail). There are two types of matching fins called the pelvic (ventral on the underbelly) and the pectoral fin (under the gills). Some fish have an extra small fin on its back next to the tail called a adipose fin. The picture below shows the fins mentioned.
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Some fish require fewer fins and the ones that do have will vary in shape and size
between species. Fins control direction, position. The tail or Caudal fin is the engine
of a fish; the dorsal and anal fin stabilizes the fish; pelvic fins are used for turning;
and the pectoral fins can lift the fish and gesture to rivals.
Like the body shape of fish
the size and shape of a fish fins is an indication of the environment that they live in. Larger
fins and a wide tail are normally found on larger fish as these are needed to maintain a correct
position in the water. Fast moving fish have smaller more streamline fins and a
large crescent shaped tail to provide plenty of power. Some fish use their fins as the only source
of propulsion and make no other body movement.
Other uses for fish fins are defence (white fin lionfish has venomous spins) mating
and even used for a type of walking or dragging.
