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

2. A History of Fishes 2 Evolutionary History  Fish have adapted to a wide range of environmental parameters Temperatures-1.8°C - 40°C pH4 - 10 O 2 Concentrations0 - Saturation Salinity0 - 90 Depths0 - 7000m

3. 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

4. Evolutionary History

6. A History of Fishes 6 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)

7. A History of Fishes 7 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

8. A History of Fishes 8 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)

9. A History of Fishes 9 Placoderms

10. A History of Fishes 10 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 This group is important

11. A History of Fishes 11 Chondrichthyes  Two distinct evolutionary lines Elasmobranchii oSharks, skates, and rays Holocephali oRatfishes and chimaeras

12. A History of Fishes 12 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

13. A History of Fishes 13 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

14. A History of Fishes 14 Actinopterygii (Ray-fined fishes)  Chondrostei Sturgeons, and paddlefishes

15. A History of Fishes 15 Actinopterygii (Ray-fined fishes)  Neopterygii Remaining 23,000+bony fishes

16. Neopterygii Osteichthyes Lineage

17. A History of Fishes 17 Evolutionary Review Ostracoderms - primitive jawless fishes No living representatives, possible relatives include hagfish and lamprey Placoderms - first jawed fishes No apparent descendants Chondrichthyes - cartilaginous fishes Holocephali - ratfishes Elasmobranchii -sharks, skates, & rays Osteichthyes - bony fishes Sarcopterygii - lobe-finned fishes Present day lungfishes and coelcanth Actinopterygii - ray-fined fishes Chondrostei - sturgeons & paddlefishes Neopterygii - remaining bony fishes

18. A History of Fishes 18 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

19. A History of Fishes 19 Physical Properties of Water  Water is 800x denser than air!  Water is incompressible  Water is a universal solvent

20. A History of Fishes 20 Have you hugged your Ichthyologist?  Ichthyology - study of fishes Describing new taxa Understanding evolutionary relationships oTaxonomy and systematics Ecology, physiology, and behavior

21. A History of Fishes 21 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

22. A History of Fishes 22 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

23. A History of Fishes 23