Characteristics of Water Continued Implications for fish biology end 2006.
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Transcript of Characteristics of Water Continued Implications for fish biology end 2006.
Characteristics of Water ContinuedImplications for fish biology
end
2006
Many other substances ionize in water:
Salts: NaCl Na+ Cl-+
Bases: NH3 + H2O NH4+ OH-+
Acids: H2CO3 H+ HCO3-+
carbonic acid
ammonia
bicarbonate
ammonium
end
Density of water
H HO
OHH
OHH
H HO
HHO
Ice: voids
voids
voids.
Covalent bond-share electrons Hydrogen bond-electrostaticend
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
Densityg/ml
Ice 0.917water 0.9999
1.000
0.996
Significance with respect to life?end
Thermal Stratification:
epilimnion
hypolimnion
thermocline
less dense
more dense
end
end
Density of water increases slightly with salinity
Salinity 0/00
Den
sity
%
0 35100
102.9
(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:
Substance Viscosity kg/m/s
acetone 0.326 x 10 -3
freshwater 1.002 x 10 –3 20 C
saltwater 34.8 g/l 1.072 x 10 –3 20 C
mercury 1.554 x 10 -3
glycerin 1.490
end
Temperature vs Viscosity
Temperature C
Vis
cosi
ty 1
0-3 k
g/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.
0
0.5
1
1.5
2
0 10 20 30 40 50
end
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 striderend
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
Substance Specific heatcopper 0.09rocks 0.2
ice 0.5water (distilled) 1.0liquid ammonia 1.23liquid hydrogen 3.4
end
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
waterneutral
buoyancy
positive buoyancy positive
buoyancy
negative buoyancy
positivebuoyancy
= H2O
> H2O
=
==
Archimedes Principle
neutral buoyancy
Fish?
end
Densities of Biological Substances:
Substance Density g/cm3
lipids 0.9freshwater (20 C) 1.002saltwater (20 C) 1.072
muscle 1.05bone (dry) 1.1
silaceous cell walls 2.0cellulose 1.5
calcium carbonate 3.0
end
Slight negative buoyancy--densities of most aquatic organisms are close to that of water (usually slightly more dense)
fish densities--1.06-1.09 g/cm3
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
http://www.und.nodak.edu/instruct/skelsch/425~1.htm
end
1. Rover Predators--moving hunters
• Terminal mouth
• Fins evenly placed (maneuverability)
• stream-linedbrassy 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 flattenednorthern 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 bearersguppies
mollies
Gambusiamosquitofishend
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 halibutend
Bottom fishes continued
• Specialized structures:
sensory structures barbels, fin rays
modified fins (darters, clingfishes)
barbels
end
sea robin
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
bluegillend
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