BIOL 404 Ichthyology the study of fishes Fishes

BIOL 404 Ichthyology - the study of fishes

Fishes w Most numerous and diverse of the major vertebrate groups w 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 branch of fish evolution. ” - P. B. Moyle & J. J. Cech, Jr. , 2004

Bony Fishes

Founders of Ichthyology

Aristotle w First known ichthyologist - 348 -322 BC w Recognized 117 species of fish, distinguished fish from whales

Peter Artedi w “Father of Ichthyology” - 1705 -1734 w Classification system of fishes w Standardized measurements and counts that remain basis of fish taxonomy today

Peter Artedi w 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 w 1707 -1778 - adapted Artedi’s system to use in his Systema Naturae - basis for all future classification systems w Extremely arrogant - some believe he may have been connected to Artedi’s death (competition between them)

Georges Cuvier w 1769 -1832 - classified all known species of fishes w Conducted detailed studies of fish anatomy w Compiled early history of ichthyology

Constantine Rafinesque w 1783 -1840 - produced the most detailed early account of fish in North America Ichthyologia Ohiensis - 1820 w Natural history of fishes of the Ohio River and its tributaries

Louis Agassiz w 1807 -1873 - important volumes on classification based on fossil fishes w Strong non-believer of evolution, but work laid foundation for evolution studies of fish w Popularizer of science to American public

Johannes Muller w 1801 -1858 - in Germany - revised Agassiz’s classification system to include most major groups still used today

Albert Gunther w 1830 -1914 - British Museum - last person to attempt to describe all species of fishes in the world

David Starr Jordan w 1851 -1931 - two major texts, plus president of Stanford w Fishes of North and Middle America w Guide to the Study of Fishes (ichthyology text)

Carl L. Hubbs w 1894 -1979 - two important texts w Classification of Fishes (standard reference) w Fishes of the Great Lakes Region

Ichthyology Jobs w Applied research - state, federal agencies - fisheries management w University teaching/research w Museum research/curatorship w Collection management w Public aquaria & aquarium hobby w Conservation agencies (protection)

Position within Animal Kingdom w Phylum Chordata w Deuterostome branch along with echinoderms & hemichordates

Within Phylum Chordata w Notochord w Dorsal, hollow nerve cord w Pharyngeal gill slits w Postanal tail

Phylum Chordata w 3 subphyla w Urochordata w Cephalochordata w Vertebrata

Subphylum Urochordata w Tunicates or sea squirts

Subphylum Cephalochordata w Lancelets

Subphylum Vertebrata w Vertebrates

Evolution & Major Groups: A Quick Overview

The First Fish w Ostracoderms appear in Cambrian fossils w Class Agnatha or Ostracodermi w Jawless, bony armor, many with bony endoskeleton w Most inhabited freshwater

The Next Fish w Ostracoderms disappear and placoderms appear in Devonian fossils w Class Placodermi w Jaws, paired fins, bony armor and endoskeleton w Not directly ancestral to higher fishes w May have given rise to cartilaginous fishes

First Chondrichthyes w Appeared in late Devonian w Differed from modern sharks w Terminal mouth w Pectoral fins broadly joined to body w No pelvic claspers

Skates & Rays w Subclass Elasmobranchii (same as sharks) w Appeared in Mesozoic w Descended from primitive sharks

Chimaeras w Subclass Holocephali w Appeared shortly after primitive sharks, did not arise from them w Arose independently from placoderms?

Osteichthyes - bony fishes w Arose in late Silurian w Probably from freshwater w Followed two lines of development: w Sarcopterygii - fleshy-finned w Actinopterygii - ray-finned

Bony Fishes

Sarcopterygii: Crossopterygii w w Lobe-finned fishes Ancestral to first amphibians Tetrapod-like bones in lobe fins Thought extinct until 1939 - coelocanth in Indian Ocean

Sarcopterygii: Crossopterygii

Sarcopterygii: Dipnoi w Lungfishes - air bladder modified into “lung” w Peaked in Paleozoic, then declined w 3 living genera: Australia, Africa, South America

Bony Fishes

Actinopterygii: Chondrostei w Cartilaginous ganoids w Paddlefish and sturgeons w Became dominant during Paleozoic, then declined

Actinopterygii: Holostei w Bony ganoids w Gars and bowfin w Became dominant during Mesozoic, then declined

Actinopterygii: Teleostei w Higher bony fishes w Common modern fishes w Became dominant during Cenozoic, still dominant

Bony Fishes