Characteristics of Water Continued Implications for fish biology end 2006

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 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

Thermal Stratification: epilimnion hypolimnion thermocline less dense more dense end

Density of water increases slightly with salinity Salinity 0 / 00 Density % (sea water) end

Viscosity: Viscosity - tendency for a fluid to resist motion within itself due to attraction among molecules. Salinity - little effect on viscosity (slight inc) Characteristics of water continued: end

Comparative Viscosities: SubstanceViscosity kg/m/s acetone0.326 x freshwater1.002 x 10 –3 20 C saltwater 34.8 g/l1.072 x 10 –3 20 Cmercury1.554 x glycerin1.490 end

Temperature vs Viscosity Temperature C Viscosity kg/m/s Viscosity doubles as temp. decreases from 25 to 0 C/ Viscosity of water offers approx. 100 x the resistance to movement as air end

Surface Tension Defn--inward adhesion of molecules at surface due to attraction of molecules surface tension of water is higher than any other liquid except mercury increases slightly with salinity decreases with temp end

spider jumping end

water strider end

Specific heat Defn--amount of energy (in calories) required to raise temperature of 1 g of substance 1 degree C water is standard with value of 1 (varies with temp but close to 1) end

Comparison of specific heat SubstanceSpecific heat copper0.09 rocks0.2 ice0.5 water (distilled)1.0 liquid ammonia1.23 liquid hydrogen3.4 end

Effects of Properties of Water on Living Organisms Density & Buoyancy Archimede’s Principle--when an object is immersed in a fluid, an upward force acts on it, equal to the weight of the fluid it displaces end

air water neutral buoyancy positive buoyancy positive buoyancy negative buoyancy positive buoyancy = H2OH2O > H2OH2O = = = Archimedes Principle neutral buoyancy Fish? end

Densities of Biological Substances: SubstanceDensity g/cm 3 lipids0.9 freshwater (20 C)1.002 saltwater (20 C)1.072 muscle1.05 bone (dry)1.1 silaceous cell walls2.0 cellulose1.5 calcium carbonate3.0 end

Slight negative buoyancy--densities of most aquatic organisms are close to that of water (usually slightly more dense) fish densities g/cm 3 end

Support Aquatic organisms are well supported due to density similarities between water and aquatic organisms Effects--reduced energy expenditure reduction or lack of support tissues end

Streamlined shapes Active fish tend to be streamlined due to high energy required for locomotion in water end

Ecological Groups of Fishes Six general categories body shape habitat general life style Clues to lifestyle Doesn’t fit all fishes 1.Rover predators 2.Lie-in-wait predators 3.Surface oriented fishes 4.Bottom fishes 5.Deep-bodied fishes 6.Eel-like fishes end

1. Rover Predators-- moving hunters Terminal mouth Fins evenly placed (maneuverability) stream-lined brassy minnow end

Ex: Salmonidae brook trout end

Ex: Percidae walleye end

Ex: Centrarchidae (basses only) largemouth bass end

2. Lie-in-Wait predator (piscivores) Terminal mouth; large w needle-like teeth Stream-lined; often elongated and thin Head flattened northern pike end

Lie-in-Wait predator (continued) Caudal fin large Dorsal and anal fins placed posteriorly Cryptic coloration end

Esocidae-pikes, pickerel, muskie muskellunge end

Lepisosteidae - gars longnose gar end

needlefish end

Sphraenidae -- barracuda longnose gar end

3. Surface-Oriented fishes Often small Upward tending mouth (superior or superterminal) Dorsoventrally flattened head Adapted to surface life Poeciliidae-live bearers guppies mollies Gambusia mosquitofish end

Four-eyed fish end

Cyprinodontidae-pupfish, killifish banded killifish end

betas archerfish Other surface oriented fishes Gambusia end

4. Bottom fishes (benthic) Swimbladder reduced or absent flattened dorsoventrally (depressed) Atlantic halibut end

Bottom fishes continued Specialized structures: sensory structures barbels, fin rays modified fins (darters, clingfishes) barbels end

sea robin end

flounders soles tonguefish Pleuronectiformes-flatfishes end

hog choker end

Acipenseridae--sturgeons lake sturgeon end

Skates & rays end

5. Deep-bodied fishes Laterally flattened (compressed) Dorsal and anal fins long Pectoral fins high on body Pelvic fins thoracic Mouth protrusible Fin spines French angelfish lookdown butterfly fish maneuverability end

Centrarchidae-crappies & sunfishes bluegill end

6. Eel-like fishes-- elongated bodies Paired fins reduced or absent Dorsal and anal fins long Scales small or absent Flexible bodies Adapted for small crevices end

American eel slime eel snake eel end

moray eel end