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A History of Fishes

A History of Fishes. Where did they come from?. Evolutionary History. Fish have adapted to a wide range of environmental parameters Temperatures -1.8°C - 40°C pH 4 - 10 O 2 Concentrations 0 - Saturation Salinity 0 - 90 Depths 0 - 7000m. Diversity and Evolution.

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A History of Fishes

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  1. A History of Fishes Where did they come from?

  2. Evolutionary History • Fish have adapted to a wide range of environmental parameters • Temperatures -1.8°C - 40°C • pH 4 - 10 • O2 Concentrations 0 - Saturation • Salinity 0 - 90 • Depths 0 - 7000m A History of Fishes

  3. Diversity and Evolution • The diversity of fishes reflects their long evolutionary history • A major challenge to ichthyologists involves unraveling the evolutionary pathways of both extant (living) and extinct taxa A History of Fishes

  4. Evolutionary History

  5. Ostracoderms • Characteristics • Lack of jaws, lack of paired fins, bony armor, and internal cartilaginous skeleton • Modern day representatives of this group include the classes Pteraspidomorphi (hagfishes) and Cephalaspidomorphi (lampreys) A History of Fishes

  6. Early Jawed fishes • Jaws are probably the greatest advancement in vertebrae evolution • This allowed for an explosion in diversity due to the different prey items that can be processed A History of Fishes

  7. Placoderms • Diverse group with a bizarre appearance • Jaws, dermal body plates, internal skeleton, and paired fins • Some were over 2 meters in size and possessed a craniovertebral joint (increased prey size) A History of Fishes

  8. Placoderms A History of Fishes

  9. This group is important Chondrichthyes • Arose during the early Paleozoic and followed a very different line of evolution • Cartilaginous fishes, 2 distinct lines of evolution, the connection between the two is poorly understood • Since cartilage does not readily fossilize not a very good fossil record • Characteristics A History of Fishes

  10. Chondrichthyes • Two distinct evolutionary lines • Elasmobranchii • Sharks, skates, and rays • Holocephali • Ratfishes and chimaeras A History of Fishes

  11. Sarcopterygii (Lobe-finned fishes) • Present day lungfishes and coelacanths • This group has paired fins which actually have muscle in the fin itself • It is this class which is believed to have given rise to the amphibians A History of Fishes

  12. Actinopterygii (Ray-fined fishes) • The most successful of all the modern fishes • Distinguished form sarcopterygians: triangular dorsal fin, paired fins without fleshy lobes, and ray finned • As this class flourishes the previous groups decline or disappear, which may show possible ecological interactions A History of Fishes

  13. Actinopterygii (Ray-fined fishes) • Chondrostei • Sturgeons, and paddlefishes A History of Fishes

  14. Actinopterygii (Ray-fined fishes) • Neopterygii • Remaining 23,000+bony fishes A History of Fishes

  15. Neopterygii Osteichthyes Lineage

  16. Chondrichthyes - cartilaginous fishes Holocephali - ratfishes Elasmobranchii -sharks, skates, & rays • Sarcopterygii - lobe-finned fishes • Present day lungfishes and coelcanth Osteichthyes - bony fishes Chondrostei - sturgeons & paddlefishes Actinopterygii - ray-fined fishes Neopterygii - remaining bony fishes Evolutionary Review • Ostracoderms - primitive jawless fishes • No living representatives, possible relatives include hagfish and lamprey • Placoderms - first jawed fishes • No apparent descendants A History of Fishes

  17. Population Distributions • By volume 97% of all water on earth is found in the worlds oceans • 58% of all fish species are marine • 41% are freshwater species • 1% move between the two habitats • Marine Habitat • 13% of marine species associate in open water • 78% live over the continental shelf A History of Fishes

  18. Physical Properties of Water • Water is 800x denser than air! • Water is incompressible • Water is a universal solvent A History of Fishes

  19. Have you hugged your Ichthyologist? • Ichthyology - study of fishes • Describing new taxa • Understanding evolutionary relationships • Taxonomy and systematics • Ecology, physiology, and behavior A History of Fishes

  20. Nomenclature • The most frustrating aspect of ichthyology is the constant changing of scientific names • These names change for several reasons: • Changes are necessary as new information is discovered concerning evolutionary history A History of Fishes

  21. Species Names • Each spp. is assigned a unique two part scientific name • Longnose Dace Rhinichthys cataractae (Valenciennes 1842) • Names are usually descriptive in some way • Rhinichthys - nose-fish • cataractae - the fast water in which it lives A History of Fishes

  22. A History of Fishes

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