rest swimming at constant velocity swim to accelerate notes and... · 2013-02-11 · fish that swim...
TRANSCRIPT
Locomotion and Swimming
•
Different categories–
Rest
–
Swimming at constant velocity–
Swim to accelerate
See review paper Langerhans
and
Reznick
2009
Types of Fishes and Habitats
•
Shape and habitat are related and integral in survival.
•
Tunas do not perform well on coral reefs
Cruisers: Fish that swim almost continuously in search for food, e.g. tunas. Red Muscle-
richly
vascularized
(blood-
carrying capacity), rich in
myoglobin
(oxygen holder and transferor into the muscles active sites) able to sustain continuous aerobic movement.
Burst Swimmers: These fish usually stay relatively in the same place such as most reef fish.
Types of Fishes by Swimming Habitat
A tuna is fusiform
similar to a torpedo and cruises through the water at very high speeds.
VARIATIONS IN BODY FORM
tuna
1) fusiforma) = torpedo-shaped b) allows minimal drag while swimmingc) best shape for a pelagic cruise
Body shapeBody shape
2)compresseda) laterally flattened (e.g., butterflyfishes&
surgeonfishes)b) allows for maneuverability in surge environmentsc) useful for demersal fishes that hover above the reefd) exception seen in flatfishes that lie on one side of the
body as benthic fishes
The compressed shape found on many reef fishes such as the butter fish
Agility for movement around the reef
support sudden bursts of acceleration
3) elongated or attenuateda) long body (e.g., trumpetfish, cornetfish, eels)b) seen in demersal fish that either hover
motionless in the water)c) seen also in benthic fishes (e.g., eels) that
hide in holes in the reef
The eel allows wiggles into small crevices where it hunts prey. Also can hover motionless
The angler fish, scorpionfish are depressed shape and use "sit and wait" strategy of hunting
4) depresseda) dorso-ventrally flattened (e.g., frogfishes,
scorpionfishes & gobies)b) broad ventral surface facilitates resting on
the bottomc) seen in many benthic fishes
Diagram of forces when a fish swims. Thrust-
force in animal's
directionLift-
force opposite in right
angles to the thrust Drag-
force opposite the
direction of movement ** All lift forces cancel out over one complete tail stroke.
Drag is minimized by the streamlined shape of the fish and a slime fishes excrete from their skin minimize frictional drag and maintains laminar (smooth) flow of water past the fish.
Gaits
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Apply to fish swimming•
Beat patterns and body shape
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Median and paired fins and body can be modified for swimming and use –
M P F.
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Body and Caudal fins are used for more rapid propulsion B C F
Provide control over movements by directing thrust, supplying lift and even acting as brakes. A fish must control its pitch, yaw, and roll.
Caudal fin--
provides thrust, and control the fishes direction
Pectorals--
act mostly as rudders and hydroplanes to control yaw and pitch. Also act as very important brakes by causing drag.
Pelvic fins--
mostly controls pitch
Dorsal/anal--
control roll
Fins/ Propulsors
Median paired Body and
caudal
Gaits combine propulsor, muscles and behavior
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Station holding•
Undulations
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Twitch•
Continuous
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Burst
STH Station holding X
PEC Pectoral fin swim�
DAC Dorsal, anal, caudal undulation
P+BCF Pectoral & body caudal O
T & C Single twitch/coast
BCF Continuous body caudal fin
B&C Burst/coast
Behaviors Change with Challenge and Species
Sphere
Disk
teardrop
Laminar flow and turbulence
http://www.whitney.ufl.edu/research_programs/liao_pages/movie-links.htm
Muscle Power and Swimming
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Slow oxidative (SO or red muscle)–
Relatively low power output but aerobic and non fatiguing
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Fast glycolytic (FG or white muscle)–
High power output but rapidly fatigues
Anoxia and Lactacidosis
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Tissue oxygen supply falls below metabolic demand
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Anerobic glycolysis with intermediary product is lactic acid
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Dissociates an equimolar amount of H+ ions•
Released H+ ions are buffered by non bicarbonate buffers or combine with bicarbonate before being eliminated from body by aerobic processing of lactic acid
Three mechanisms to restore pH during lactacidosis
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Adjustment of plasma CO2•
Aerobic processing of lactic acid by breakdown to CO2 and re-synthesis to glycogen
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Elimination of surplus H + ions from the body fluids
Environmental hypoxia
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Metabolism provides continuous load of CO2
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Endogenous production of acid base relevant ions rises tremendously during extreme muscular activity and during extreme hypoxia.
Transepithelial acid base relevant ion transfer
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Main mechanism for fish acid base regulation
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Gill surface epithelium key for fish
Limits of Plasma Bicarbonate
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Extent of compensation is function of ratio between plasma and environmental bicarbonate concentration.
Tufts et al. 1991
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Wild Atlantic salmon lactacidosis•
Exercised to exhaustion
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Acid base regulation observed
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Doral cannula•
48 h recovery
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Baseline–
pH, CO2, O2, PO2, hct, plasma Co2, lactate, erythrocyte pH,
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Exhaustion by chasing
Measures•
pH –
direct
•
O2 -
direct•
Erythrocyte Hb
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CO2 blood and plasma –
GC•
Arterial CO2 and plasma bicarbonate –
calculated
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Nucleotide triphosphate
NTP
= adenosine triphosphate
(ATP), guanosine triphosphate
(GTP), cytidine triphosphate
(CTP), thymidine triphosphate
(TTP) and uridine triphosphate
(UTP) ENERGY
pH
Plasma bicarbonate
Arterial CO2 tension
Lactate
Metabolic Proton load H+
H+ deficit
Hemoglobin: oxygen carriage
Erythrocyte pH
Erythrocyte NTP (nucleotide triphosphate) concentration
Arterial oxygen versus erythrocyte pH
Conclusions
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Burst activity associated with marked acidosis•
Most severe 2 h immediately following exercise
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RBC sensitive to adrenergic stimulation in vitro•
Perhaps RBC are aged in migrating fish
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Spleen may be more important than regulation of pH following exhaustive exercise in migrating Atlantic salmon with increase number rbc
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Delayed mortality in catch and release fishing??
Handouts for summary of mechanisms on class web and preparation for discussions Tuesday
Exercise
Hypoxia
http://www.cnr.uidaho.edu/fish511/presentations.htm
Bradycardia (reduced heart rate).
Mediated by increased vagal (parasympathetic) stimulation of the heart. This is a conserved reflex seen in a
vertebrate classes (particularly important in diving mammals for
conservation of oxygen).
Function: (a) Most likely a secondary response
peripheral vasoconstriction, an important mechanism for shunting oxygenated blood away from
hypoxia-resistant tissues (skeletal muscle
conserving it for hypoxia-sensitive tissue (heart, retina, brain). Other possible advantages of
bradycardia
are: (b) increased ventricular fil
time, increasing ventricular volume and so stretch of heart muscle, force of contraction, and efficiency of pumping, and (c) increased strok
volume, increasing systolic pulse pressure and so facilitating lamellar recruitment.
2. Increased gill ventilation. Develops more slowly than
bradycardia. Probably triggered by effect of lowered blood PO2 on receptors in the b
first gill arch. Function: increases the amount of O2
delivered to the gills per unit time.
3. Increased gill blood flow. Increased pulse pressure results in lamellar recruitment, augmented by decreased vascular resistance on the affer
lamellar arteriole side (beta-adrenergic
effect) and possibly by increased resistance on the efferent lamellar arteriole side (alpha-adrenergic
effect). Function: Increases effective gill surface area and so increases oxygen uptake.
4. Enhanced H+ excretion by
RBCs; also, Na+
and
Cl–
uptake, resulting in swelling and thereby decreasing intra-RBC concentrations of ATP
other organic phosphates. Function: Compensatory increase in affinity of hemoglobin for O2
.
5. Facilitated acid-base regulation by the gills. The exchange of H+
(out) for Na+
(in) is increased, while the exchange of HCO3–
(out) for
Cl
decreased. Function: buffering and elimination of excess H+
created by disassociation of lactic acid, a product of anaerobic metabolism, helping to restore (raise) blood pH.
6. Use of "venous reserve". As ambient PO2
falls, arterial and venous PO2
also decline. Because of the shape of the blood loading curve,
the e
to deliver more oxygen to the tissue per unit volume of blood (see figure with exercise handout).
These compensatory changes in heart and gill function allow oxygen uptake to be maintained over a range of PO2
(although activity is progr
constrained). Below the critical" PO2
, compensatory mechanisms are no longer adequate, and O2 uptake declines. Some tissues (e.g., brain
sensitive to low PO2 but are "protected" for some period of time by preferential blood flow; other tissues (white muscle, more than 60% of mass) have a relatively low energy requirement and a high anaerobic capacity, so can tolerate long periods of hypoxia without damage.