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BIOL 404 Ichthyology. - the study of fishes. Fishes. Most numerous and diverse of the major vertebrate groups More classes of fishes than all other vertebrates combined. Status of Fish.
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BIOL 404 Ichthyology - the study of fishes
Fishes • Most numerous and diverse of the major vertebrate groups • More classes of fishes than all other vertebrates combined
Status of Fish “Humans are not the pinnacle of evolutionary progress but only an aberrant side branchof fish evolution.” - P.B. Moyle & J.J. Cech, Jr., 2004
Aristotle • First known ichthyologist - 348-322 BC • Recognized 117 species of fish, distinguished fish from whales
Peter Artedi • “Father of Ichthyology” - 1705-1734 • Classification system of fishes • Standardized measurements and counts that remain basis of fish taxonomy today
Peter Artedi • Friend of Carolus Linneaus, who published his works after Artedi died by drowning in a canal in Amsterdam after a night of drinking
Carolus Linneaus • 1707-1778 - adapted Artedi’s system to use in his Systema Naturae - basis for all future classification systems • Extremely arrogant - some believe he may have been connected to Artedi’s death (competition between them)
Georges Cuvier • 1769-1832 - classified all known species of fishes • Conducted detailed studies of fish anatomy • Compiled early history of ichthyology
Constantine Rafinesque • 1783-1840 - produced the most detailed early account of fish in North America - Ichthyologia Ohiensis - 1820 • Natural history of fishes of the Ohio River and its tributaries
Louis Agassiz • 1807-1873 - important volumes on classification based on fossil fishes • Strong non-believer of evolution, but work laid foundation for evolution studies of fish • Popularizer of science to American public
Johannes Muller • 1801-1858 - in Germany - revised Agassiz’s classification system to include most major groups still used today
Albert Gunther • 1830-1914 - British Museum - last person to attempt to describe all species of fishes in the world
David Starr Jordan • 1851-1931 - two major texts, plus president of Stanford • Fishes of North and Middle America • Guide to the Study of Fishes (ichthyology text)
Carl L. Hubbs • 1894-1979 - two important texts • Classification of Fishes (standard reference) • Fishes of the Great Lakes Region
Ichthyology Jobs • Applied research - state, federal agencies - fisheries management • University teaching/research • Museum research/curatorship • Collection management • Public aquaria & aquarium hobby • Conservation agencies (protection)
Position within Animal Kingdom • Phylum Chordata • Deuterostome branch along with echinoderms & hemichordates
Within Phylum Chordata • Notochord • Dorsal, hollow nerve cord • Pharyngeal gill slits • Postanal tail
Phylum Chordata • 3 subphyla • Urochordata • Cephalochordata • Vertebrata
Subphylum Urochordata • Tunicates or sea squirts
Subphylum Cephalochordata • Lancelets
Subphylum Vertebrata • Vertebrates
The First Fish • Ostracoderms appear in Cambrian fossils • Class Agnatha or Ostracodermi • Jawless, bony armor, many with bony endoskeleton • Most inhabited freshwater
The Next Fish • Ostracoderms disappear and placoderms appear in Devonian fossils • Class Placodermi • Jaws, paired fins, bony armor and endoskeleton • Not directly ancestral to higher fishes • May have given rise to cartilaginous fishes
First Chondrichthyes • Appeared in late Devonian • Differed from modern sharks • Terminal mouth • Pectoral fins broadly joined to body • No pelvic claspers
Skates & Rays • Subclass Elasmobranchii (same as sharks) • Appeared in Mesozoic • Descended from primitive sharks
Chimaeras • Subclass Holocephali • Appeared shortly after primitive sharks, did not arise from them • Arose independently from placoderms?
Osteichthyes - bony fishes • Arose in late Silurian • Probably from freshwater • Followed two lines of development: • Sarcopterygii - fleshy-finned • Actinopterygii - ray-finned
Sarcopterygii: Crossopterygii • Lobe-finned fishes • Ancestral to first amphibians • Tetrapod-like bones in lobe fins • Thought extinct until 1939 - coelocanth in Indian Ocean
Sarcopterygii: Dipnoi • Lungfishes - air bladder modified into “lung” • Peaked in Paleozoic, then declined • 3 living genera: Australia, Africa, South America
Actinopterygii: Chondrostei • Cartilaginous ganoids • Paddlefish and sturgeons • Became dominant during Paleozoic, then declined
Actinopterygii: Holostei • Bony ganoids • Gars and bowfin • Became dominant during Mesozoic, then declined
Actinopterygii: Teleostei • Higher bony fishes • Common modern fishes • Became dominant during Cenozoic, still dominant