FINS IN FISHES ZOOLOGY.pptx

Fins in Fishes

1. FINS IN FISHES

2. INTRODUCTION 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 .

3. TYPES OF FINS IN FISHES PECTORAL FIN DORSAL FIN PELVIC FIN CAUDAL FIN ANAL FIN

4. PECTORAL FINS

5. 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.

6. DORSAL FINS

7. 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 .

8. TYPES OF DORSAL FINS

9. PELVIC FINS (VENTRAL FIN)

10. 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.

11. CAUDAL FINS

12. 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.

13. TYPES OF CAUDAL FINS IN FISHES PROTOCERCAL CAUDAL FIN HETEROCERCAL CAUDAL FIN HOMOCERCAL CAUDAL FIN

14. PROTOCERCAL CAUDAL FIN

15. 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.

16. HETEROCERCAL CAUDAL FIN

17. 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 )

18. HOMOCERCAL CAUDAL FIN

19. 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.

20. ANAL FINS

21. 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.

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