Reading Assignment:
• Chapter 13--Evolution
coelacanthend
2006
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 24• Project due at end of semester• Purposes: synthesis; lit. search; sci. writing
end
Project Topics:
• Select a fish-related topic that is in an area of interest to you--ecology, behavior, physiology
• Topic should be sufficiently narrow for an in-depth treatment (10-12 pages)
– sea lamprey--too broad– behavioral responses of fish to sea lamprey
attack--better
end
• Try to do some synthesis rather than a report– develop an hypothesis or competing
hypotheses; find studies that support or refute them
– or present and evaluate competing hypotheses– learn enough about the subject to make your
own contribution
end
• Access the primary literature--journals
• Do a subject search using:– Biological Abstracts (now avail. In e form
http://www.library.und.edu/research/articleindexes.php )
– Zoological Record– Fisheries Review– Aquatic Sciences and Fisheries Abstracts– Current Contents
http://www.und.edu/dept/library/
end
Develop specific objectives:
• The objectives of this study are to:– describe modes of sea lamprey attack– describe behavioral responses of hosts to
parasitism by sea lampreys– use existing literature to test the hypothesis that
lampreys select hosts of sufficient size to minimize host mortality
end
Develop an Outline:• Introduction
• Methods
• Results and Discussion
• Literature Cited
end
end
Physical Aspects of Aquatic Environments
H H
OWater:
104.5
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
cell membrane—phospholipid bi-layer
Does this remind you of anything?
end
carboxyl group
hydrocarbon
Ionization of water:
2H2O H3O+ + OH-
hydronium ion hydroxide ion.
H+ H+ . H2O
end
How much does water ionize?
Hint: pH = -log H+
10log
10-7 g-ions/l
0.0000001 g-ions/l
Note: inverse log scaleend
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
end
Viscosity:
• Viscosity - tendency for a fluid to resist motion within itself due to attraction among molecules.
• Salinity - little effect on viscosity (slight inc)
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 1degree 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?
endend
density
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 Groupings of Fishes
Body shape--6 general categories
habitat
body shape
general life style
end
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
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
Surface-Oriented fishes
• Often small
• Upward tending mouth (superior or superterminal
• Dorsoventrally flattened head
• Adapted to surface
end
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