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Ichthyology

Ichthyology. The study of fishes. Over half of all vertebrates are fishes! Fishes have the following 5 characteristics in common: Vertebral column : internal skeleton spine surrounding the dorsal nerve cord

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Ichthyology

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  1. Ichthyology The study of fishes

  2. Over half of all vertebrates are fishes! • Fishes have the following 5 characteristics in common: • Vertebral column: internal skeleton spine surrounding the dorsal nerve cord • Jaws and paired appendages: all fish except lampreys and hagfishes have both. Jaws allow fishes to eat things bigger then their mouths • Internal Gills: used for respiration • Single-loop blood circulation: blood goes from heart to gills to rest of body and back to heart • Nutritional deficiencies: unable to make certain amino acids and must consume them (just like all of their vertebrate descendants!)

  3. Evolution of the jaw: • Fundamentally important evolutionary advance • Evolved from the most anterior of a series of gill arches

  4. The evolution of shark teeth: • Sharks were among the first vertebrates to develop teeth • Evolved from rough scales on the skin and are not set into the jaw like human teeth • Not firmly anchored and easily lost • A shark may loose more than 20,000 teeth in it’s lifetime

  5. The Lateral Line System: • Supplements the fish’s sense of hearing (yes, fish have ears too) • Series of canals running length of the body • Within these canals are hair cells with cilia that detect water movement • This what enables the fish to detect prey and swim in synchrony with it’s school

  6. The Swim Bladder • Gas-filled sac that allows bony fish to regulate their buoyant density and adjust their depth effortlessly • Organs are filled and drained of nitrogen and oxygen internally

  7. Gills! • Fish allow water to flow over the gills for gas exchange • Bony fish have an operculum • Hard plate covering the gills • Bony fish can pump water over their gills, sharks can not

  8. Fish are divided into 7 classes: • Sarcopterygii, lobe-finned fishes • Actinopterygii, Ray-finned fishes • Chondrichthyes, Sharks and rays • Cephalaspidomorphi, Lampreys • Myxini, Hagfishes • Placodermi, Armored fishes • Acanthodii & Ostracoderms, Spiny fishes

  9. Class Myxini: The Hagfishes http://www.youtube.com/watch?v=Bb2EOP3ohnE&feature=player_embedded

  10. Cephalaspidomorphi: The Lampreys!

  11. Sarcopterygii: Lobe-finned Fishes!

  12. Placodermii: Armored Fishes! (extinct)

  13. Chondrichthyes: The Sharks and Rays!

  14. Actinopterygii: The Ray-Finned Fishes!

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