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External Anatomy of Fish

External Anatomy of Fish

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External Anatomy of Fish

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  1. External Anatomy of Fish

  2. The Head

  3. Mouth Shape/ Position • Superior Mouth • Also known as an undershot or upturned mouth • Eats food above the fish • May eat at the water’s surface • Terminal Mouth • Eats food in front of it • Inferior Mouth • Also known as an underslung mouth • Eats food below it • May eat off of the bottom

  4. Operculum & Gills • Gills • Allows gas exchange for the fish • Through the gills, fish are able to absorb oxygen and give off carbon dioxide • Operculum • The gill cover

  5. Barbels • Also known as whiskers • located under the mouth of a fish • are tactile and taste organs used for locating food in dark or muddy waters

  6. The Body

  7. Body shapes • Ovate Body • Slow swimmer • Difficult for predators to swallow • Fusiform Body • High speed swimmers • The most common form • Truncate • A shortened type of fusiform • Elongate/Serpentine • Hides in rocks and weeds

  8. Body Covering • covered with scales, which protect the body • Most fish get extra protection from a layer of slime that covers their scales called mucus.

  9. Scales • Made of calcium, they are outgrowths of the skin • They overlap like shingles on a roof so that the skin of the fish is not exposed • The scales of a fish lie in pockets in the dermis and come out of the connective tissue. • Scales do not stick out of a fish but are covered by the Epithelial layer. • The ridges and the spaces on some types of scales become records of age and growth rate.

  10. Cycloid scales Have a smooth edge on the backside Found on soft-rayed fish Ctenoid scales Have teeth-like projections along the backside Found on spiny-rayed scales Placoid scales Are similar to teeth Made of dentin covered by enamel Ganoid scales Flat and basal looking They overlap very little Types of Scales

  11. Mucus (Slime) • helps them move through the water better by reducing friction • is a barrier to the entry of parasites, fungi, and disease organisms that might infest the fish • it seals in the fish’s body fluids so that they are not diluted by the watery surroundings • makes the fish slippery when predators try to grab hold

  12. Lateral Line • is a series of fluid-filled ducts located just under the scales • picks up vibrations in the water • fish are able to detect predators, find food, and navigate more efficiently • help the fish detect water pressure changes • It can detect minute electrical currents in the water • It runs in a semi line from the gills to the tail fin. It can be easily seen in fish as a band of darker looking scales running along the side.

  13. Peduncle • The edge of the tail fin that lies on the end or outside of the caudal fin

  14. Types of Fins

  15. Fins • used for movement, stability, nest-building, spawning, and as tactile organs • can be single or paired

  16. Tail fin • Also known as the caudal fin • Used for propulsion • Large, elongated caudal fins are often used to attract mates.

  17. Types of Caudal Fins • Heterocercal Tail • the vertebrae extend into a larger lobe of the tail or that the tail is asymmetrical • Fast swimmer • Constantly moving • Two types • Epicercal means that the upper lobe is longer • Hypocercal means that the lower lobe is longer

  18. ProtocercalTail • the caudal fin extends around the vertebral column • Slow swimmer • Bottom wriggler • Diphycercal Tail • three-lobed caudal fin • the vertebrae extend all the way to the end of the tail

  19. HomocercalTail • the vertebrae do not extend into a lobe and the fin is more or less symmetrical • Rounded • Good at turning • Fast for short distances • Often predators • Truncate Tail • Good at turning • Slower swimmer • Forked Tail • Fast swimmer • Lunate Tail • Long distance swimmer

  20. Anal Fin • A single fin • Located on the underside of the body just forward of the caudal fin • Used to stabilize the fish while it is swimming • Long anal fins that are moved in an undulating manner are used for propulsion

  21. Pelvic or Ventral Fins • A paired fin • located forward of the anal fin • are used to provide further stability in swimming • times these fins are modified as long, thread-like fins used as a tactile organ • Relate to the hind legs

  22. Pectoral Fin • A paired fin • located near the gill cover • used for manoeuvring the fish • Sometimes the pectoral fins are equipped with spines for defence • Related to the front legs or arms

  23. Dorsal fin • A single fin, but some species may have a second fin • located on the back of the fish • serves to help balance the fish while swimming • rays of this fin are often sharp, and a spine is often present

  24. Adipose fin • is a tiny fin found between the dorsal and caudal fins on some fish • a soft, fleshy fin

  25. Finlets • small fins • generally behind the dorsal and anal fins • they are rayless and non-retractable

  26. Caudal Keel • May be single, paired, or double pairs • a lateral ridge on the caudal peduncle • usually composed of scutes • provides stability and support to the caudal fin