A History of Fishes

2 Evolutionary History  Fish have adapted to a wide range of environmental parameters Temperatures-1.8°C - 40°C pH O 2 Concentrations0 - Saturation Salinity Depths m

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

Evolutionary History

A History of Fishes 6 Conodonts

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8 Ostracoderms  Characteristics: 1.Lack of jaws 2.Lack of paired fins 3.Bony armor 4.Internal cartilaginous skeleton  Modern day representatives of this group: Class Pteraspidomorphi (hagfishes) Class Cephalaspidomorphi (lampreys)

A History of Fishes 9 Ostracoderms

A History of Fishes 10 Early Jawed fishes  Gnathostomes Jaws are probably the greatest advancement in vertebrate evolution oThis allowed for an explosion in diversity due to the different prey items that can be processed

A History of Fishes 11 Placoderms  Diverse group with a bizarre appearance 1.Jaws 2.Dermal body plates 3.Internal skeleton 4.Paired fins  Some were over 6 meters in size and possessed a craniovertebral joint

A History of Fishes 12 Placoderms Dinichthys Craniovertebral joint

A History of Fishes 13 Placoderms Gemuendina Bothriolepis

A History of Fishes 14 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 oSince cartilage does not readily fossilize not a very good fossil record  Characteristics

A History of Fishes 15 Chondrichthyes

A History of Fishes 16 Chondrichthyes  Two distinct evolutionary lines 1.Subclass Elasmobranchii oSharks, skates, and rays

A History of Fishes 17 Chondrichthyes  Two distinct evolutionary lines 2.Subclass Holocephali oRatfishes or chimaeras

A History of Fishes 18 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 19 Actinopterygii (Ray-finned fishes)  The most successful of all the modern fishes 1.Triangular dorsal fin 2.Paired fins without fleshy lobes 3.Ray-finned

A History of Fishes 20 Actinopterygii (Ray-finned fishes)  Subclass Chondrostei Sturgeons, and paddlefishes

A History of Fishes 21 Actinopterygii (Ray-finned fishes)  Subclass Neopterygii Remaining 23,000+ bony fishes

A History of Fishes 22 Evolutionary Review Ostracoderms - primitive jawless fishes No living representatives, possible relatives include hagfish and lamprey Class Placodermi - first jawed fishes No apparent descendants Class Chondrichthyes - cartilaginous fishes Subclass Holocephali - ratfishes Subclass Elasmobranchii - sharks, skates, & rays Class Osteichthyes - bony fishes Subclass Sarcopterygii - lobe-finned fishes Present day lungfishes and coelacanth Subclass Actinopterygii - ray-finned fishes Infraclass Chondrostei - sturgeons & paddlefishes Infraclass Neopterygii - remaining bony fishes

A History of Fishes 23 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 24 Physical Properties of Water  Water is 800x denser than air!  Water is incompressible  Water is a universal solvent

A History of Fishes 25 Have you hugged your Ichthyologist?  Ichthyology - study of fishes Describing new taxa Understanding evolutionary relationships oTaxonomy and systematics Ecology, physiology, and behavior

A History of Fishes 26 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 27 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 oRhinichthys - nose-fish ocataractae - the fast water in which it lives

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