Reading Assignment: Chapter 12--Systematics, genetics, and speciation basking shark end

Freshwater vs. Saltwater 58 % of fishes are marine 41 % freshwater Earth’s waters: –97% saltwater; 70% of surface of Earth – % freshwater; 1% of Earth surface end

Diversity of Life Styles: nekton (self mobile) plankton (drifters) bottom dwellers (benthic) open water (pelagic) surface oriented (epipelagic) carnivorous omnivorous herbivorous filter feeders parasites diadromous end

Fish Diversity Phylum Subphylum Superclass Class ChondrichthyesActinopterygiiCephalaspidomorphi Myxini Gnathostomata (jaws) hagfishlampreyscartilaginous fishes sharks, skates, rays ray-finned fishes end Chordata Craniatata (cranium) other verts?

Why do we recognize fish? Constraints & Characteristics of water –density (800 x denser than air) –support (lighter skeleton, diminished limbs) –viscosity (streamlined shapes) Evolutionary convergence Absence of divergence end

Thoughts on the Evolution of Fishes What are general characteristics of fishes and vertebrates? (consider their protist and invertebrate ancestors) size locomotion bilateral symmetry end

Advantages of size: Survivability: predator avoidance prey availability environmental selection and avoidance end

Requirements for size: support (skeletal system) mechanisms of locomotion systems end

Simplest form of locomotion in cordates Direction of locomotion Notochord--flexible, incompress. sinusoidal movement end

Vertebral column: vertebrae discs Flexible incompressible end

Caudal fin Pectoral fins Pelvic finsAnal fin Dorsal fin--raysDorsal fin--spines Caudal peduncle end

Physical Aspects of Aquatic Environments HH O Water:  covalent bond - + polar molecule end

Water is a polar molecule dissolves polar substances--salts, etc doesn’t dissolve non-polar substances--fats, oils, waxes end

oil Soap molecule: polar non-polar end

Ionization of water: 2H 2 OH3O+H3O+ +OH - hydronium ion hydroxide ion H+H+ H +. H 2 O end

How much does water ionize? Hint: pH = -log H+ 10 log g-ions/l g-ions/l Note: inverse log scale end

Many other substances ionize in water: Salts: NaCl Na + Cl - + Bases: NH 3 + H 2 O NH 4 + OH - + Acids: H 2 CO 3 H+H+ HCO carbonic acid ammonia bicarbonate ammonium end

Density of water H H O O H H O H H HH O HH O Ice: voids Covalent bond-share electrons Hydrogen bond-electrostatic end

As temp of ice increases: Molecules vibrate more rapidly hydrogen bonds begin to break free molecules fill voids water becomes densest vibrations increase in amplitude; intermolecular distances increase TEMP. 0 °C 3.94 °C 100 °C Density g/ml Ice water Significance with respect to life? end

Density of water increases slightly with salinity salinity density end

Stratification: epilimnion hypolimnion thermocline less dense more dense end

Semester Projects 100 point project usually library research leading to a written paper do some preliminary research to define topic have topics approved by September 30 Project due at end of semester end

Engineer a new species: Given a certain biomass to work with, how big would you make them? Why? –Considerations related to size extremes survivability versus cost of losing an individual What other characteristics would you choose? Why? –locomotion?, symmetry?, survivability? Thought experiment: end

Evolutionary race among predators and prey: sizelocomotion bilateral symmetry guidance end