2. Most distinctive anatomical
feature of a fish.
Composed of bony spines or rays
protruding from the body with skin
covering them and joining them
together.
Either in a webbed fashion or to a
flipper seen.
WEBBED FASHION: In most of
Bony Fishes.
FLIPPER FASHION: As seen in
Shark.
6. Pectoral Fins are located on
both sides usually just behind the
operculum.
It is homologous to the
forelimbs of tetrapods .
It provides supports during
swimming.
It creates the dynamic lifting
force and also helps the fish to
turn left or right.
7.
8. Located on the back .
A fish can have upto 3 dorsal fins ,i.e.
Proximal, Middle, Distal.
In rock hard,spinous fins the distal is
often fused to the middle or not present
at all.
Dorsal fins protect the fish against
rolling and stabilze them in water.
The bones that support the dorsal fin
are called Pterygiophore.
12. Located ventrally below and behind the
pectoral fin
Homologous to hindlimbs of tetrapods.
The pelvic fin assists the fish in going up
and down through the water, turning
sharply.
In Gobies , the pelvic fin are often fused
into a single sucker disk. This can be used
to attach to objects.
Pelvic fins can take many positions along
the ventral surface of the fish.
13.
14. The caudal fin is well developed in most
fishes
It plays the most important role in
forward propulsion during swimming.
In bottom dwelling rays, the caudal fin
tends to become reduced.
In the sting rays the caudal fin is lacking.
The caudal fin exhibits different shapes in
different groups of fishes correlated with
their habits.
18. This type of caudal fin is regarded to be the most
primitive type.
The vertebral column extends up to the tip of the tail
and divides the caudal fin into two equal halves.
The dorsal half is called epichordal lobe .
the ventral half is known as hypochordal lobe.
The epichordal and hypochordal parts of the caudal fin
are equal in size and symmetrical.
It occurs in modem cyclostomes, primitive sharks,
Holocephali (Chimaera), living Dipnoi (lung-fishes), living
crossopterygii (Latimeria), many larval teleosts and deep
sea fishes.
19.
20. It is the intermediate type in which vertebral column
bends upwards and reaches up to the tip of the more
prominent dorsal lobe.
This makes the caudal fin strongly asymmetrical.
Heterocercal caudal fin is characteristic of bottom
feeders with ventral mouth and without swim-bladder
(air-bladder).
The strokes of larger dorsal lobe in swimming serve to
direct fish towards bottom.
This type of caudal fin is found in modem
elasmobranchs, extinct osteolepid crossopterygian
(Osteolepis), extinct dipnoans (Dipterus) and living
holosteans (Acipenser, Polyodon)
21.
22. This is the advanced and most common type of
caudal fin.
The homocercal (Gr., homos = common, alike)
caudal fin is the characteristic of the higher bony
fishes (teleosts).
It is symmetrical externally but internally it is
asymmetrical.
The posterior end of vertebral column is turned
upwards and becomes greatly reduced.
23.
24. Located on the ventral surface behind the
Anus or Cloaca.
Supports the dorsal fin by providing the
fish with more stability in water controlling
the rolling motion.
This fin is also used to stabilibze the fish
while swimming.
