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