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What is a shoal?
groups of fish remaining together for social reasons
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What is a school?
synchronized and polarized swimming groups
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What 2 cues do fish use to school?
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What are the 2 main structures of schools?
- shape depends on function
- usually a single species, can be mixed
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What are the 4 advantages of schooling?
- hydrodynamic advantage
- avoiding predation
- foraging
- migration
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What are the ways of avoiding predation in schools?
- simple avoidance - pred req. narrow search field
- dilution effect
- evasion - from swift cooperative behavior
- pred. confusion
- mobbing
- schreckstoff
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What are the costs to foraging in schools?
increased competition for food already found
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What are the benefits of foraging in schools?
- faster location of food
- more time for feeding
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What are the advantages of migrating in schools?
- more accurate homing of salmon
- culture transfer of information (juv. learn where to forage)
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What is migration?
- mass movement from one habitat to another
- involves regularity in time, or according to life history stage
- can be active or passive
- used for feeding, breeding, or wintering
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What are the 3 main types of migration (based on water types)?
- diadromy (3 subsets)
- oceanodromy - wholly w/i SQ
- potamodromy - wholly w/i FW
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What are the 3 subsets of diadromy?
- anadromy - SW to FW to breed
- catadromy - FW to SW to breed
- amphidromy - not for breeding, both FW and SW
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What are the 3 main types of migration (based on strategy)?
- wintering - climate factors
- spawning - gametic/larval factors
- feeding - trophic factors
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What types of navigational cues to fishes use to migrate?
- olfactory - imprinting (common)
- sun compass
- geomagnetic/geoelectric fields
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What is the primary purpose of swimming?
- feed
- avoid being eaten
- *very strong selective force
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What has the swimming system evolved to do?
- minimize energy req (pikes)
- increase accel. and speed (tuna)
- improve maneuverability (perch)
- compromise bw and fine tuning of these 3
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What is motion?
- a balance bw two hydrodynamic forces
- those that resist, and
- those that generate propulsion
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What is resistance equal to?
inertia + drag
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What is inertia?
energy req. to start something in motion
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What is drag?
- force that acts backwards along the direction of motion
- -friction drag
- -pressure drag
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What is friction drag?
- "stickiness" of water along side
- water molec. bouncing off fish
- proportional to velocity of water or fish and body surface area
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What is pressure drag?
- caused by distortions of flow around fish's body
- net pressure diff. bw head (hi pressure) and tail (lo pres.)
- proportional to velocity and body shape
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How can drag be minimized?
- fusiform body shape
- mucous/slime
- tuck fins into folds in body
- vortex generators - stabilize boundary layer)
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What 2 forces enhance propulsion?
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What is lift?
force perpendicular for direction of motion
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What is thrust?
linear force exerted by fish to propel itself
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What are the 2 ways to generate thrust?
- undulatory (head to tail)
- oscillatory (side-to-side; paired and caudal fins)
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What are the 2 components of normal force?
- side (lateral) - cxl when body/tail move back and forth
- thrust (fwd, along length of body)
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How are contractions generated to create undulatory motion?
interaction bw skeleton (head/skull, vertebral columns, appendicular), muscles and fins
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What are the components of the vertebral column?
- vertebrae with centra, neural spine (dorsal; spinal cord), hemal spine (ventral; caudal veins/arteries)
- hemal spine in body cavity mod. into pleural rib
- ligaments attach centra (flexible)
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What skeletal feature helps with braking and maneuverability?
appendicular skeleton - pelvic and pectoral girdles
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What are the components of the pectoral fin/girdle?
- cleithrum
- pect. fins attach at base of girdle
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What are the components of the pelvic fin/girdle?
basipterygia attach pelvic fin to girdle (not to vert. column)
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What are the 3 main muscle types?
- flexors - extensors (lateral musc)
- protractors - retractors
- adductors - abductors
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What do flexors and extensors do?
lateral musc. along sides of body move vert. side to side
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What do protractors and retractors do?
erect and depress doral and anal fin
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What do adductor and abductors do?
move paired fins twds and away from body
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How does cruising work?
- wave of contraction down length of body
- spinal nerves linked to myomere
- wave of innerv. contracts in sequence
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How does acceleration work?
- all musc. on one side contract simultaneously
- Mauthner cells (giant axons) in teleosts
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What is red muscle good for?
- slow contractions; cruising
- little mass (superficial only)
- lots of myoglobin
- more extensive vein/cap. develp
- slender, longer; faster diffusion
- higher density of mitochondria (oxidative metabolism)
- more fat; fast recovery (aerobic)
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What is white musc. good for?
- faster contraction speed, rapid burst (fatgiues quickly)
- lots of mass
- less myoglobin
- lower blood supply
- thicker and shorter
- low density mitochondria
- less fat (anaerobic)
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What are the 2 kinds of fins used in oscillatory swimming?
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What are wing-like fins?
- thrust generated like a wing and generates lift
- ie. caudal fin of tuna
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What are the advantages to a narrow caudal peduncle and wing-like fins?
- minimal drag, very efficient
- fast once started
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What are the disadvantages of wing-like fins?
- poor quick start
- poor turning
- poor hovering
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What are oar-like fins?
- use pectorals to scull like oars
- push water back (power stroke) and return collapsed fins horizontally
- -figure 8 motion
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What are the 5 major fins?
- dorsal
- anal
- caudal
- pectoral
- pelvic
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What is the main function of the caudal fin?
propulsion (und, osc) and as vane/rudder
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What is the main function of the dorsal and anal fin?
- propulsion (und)
- prevents roll
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What is the main function of the pelvics?
- act as hydrofoils
- control pitch
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What is the main function of the pectorals?
- propulsion (sculling)
- control yaw
- turning and brakes
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What is the advantage to depth regulation (buoyancy)?
vertical structuring of food, predation, temperature, light, oxygen
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What is depth regulation?
generating lift because fish will tend to sink
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How do you generate lift?
- pectoral fins in sharks/tuna
- heterocercal tail of sharks
- hover via pectorals
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What is the advantage to generating lift?
move freely up and down in the water column
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What are the disadvantages to generating lift?
- high energy expenditure
- must maintain certain speed of movement
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Who benefits most from generating lift?
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How do you reduce dense materials for depth regulation?
- reduce calcification of bones
- reduce protein in muscles
- increase in water
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What is the advantage to reducing dense materials?
lift doesn't very with depth
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What is the disadvantage to reducing dense materials?
restricts activity
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Who benefits most from reduction of dense materials?
deep sea fishes
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How does storage of fats/oils help with buoyancy?
- squalene - low density hydrocarbon stored in liver of squaloid sharks
- wax esters - coelacanth
- lipids in bones
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What is the advantage to storing oils/fats for buoyancy?
lift doesn't vary with depth
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What are the disadvantages to storing oils/fats for buoyancy?
- fine-tuning is difficult
- buoyancy regulation linked to metabolism
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What is a gas bladder/swim bladder?
- gas-filled sac in upper part of body below vert. column and kidneys
- storage of gas
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What are the advantages of a swim bladder?
- gas is light
- precise control possible
- no relationship to energy storage
- energetically inexpensive
- many strategies possible: sit and wait, slow cruising, hovering
- other uses: sound producer/detector
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What are the disadvantages of a swimbladder?
- lift varies with depth
- large depth changes not practical over short time period
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How is the swim bladder structured?
- derived as outpocket of esophagus
- physostomous - primitive (connect to esophagus through pneumatic duct)
- physoclistous - advanced (closed, pneumatic duct sealed off)
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What is Boyle's law?
- at a constant temperature, volume varies inversely with absolute pressure
- P1V1=P2V2
- Pressure increases 1atm for every 10m in depth
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What is the physostome solution for letting gas in/out?
secretion (gulp air) and burp
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What is the disadvantage to the physostome solution?
fish dependent on surface if gulping air
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What is the physoclistous solution for letting gas in/out?
resorption and secretion
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How does resorption work?
- removal of gases via blood
- wall of swb not permeable - poorly vascularized, line with guanine crystals
- use sphincter to regulate gas entering resorptive area
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How does secretion work?
- addition of gas - physostomous
- diffusion of gases from blood in gas gland
- problem: need high partial pressure/concentration of gas in blood
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What are the 4 general ways to increase pp/concentration of gas in blood?
- acidification releases O2 from hemoglobin (Bohr, Root)
- Acid releases CO2 from bicarbonate in blood
- Lactate and H ions reduce solubility of gases in aq. solutions - salting-out effect
- efficiency of CCE (rete mirabile)
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What is the Bohr effect?
- reduced affinity of O2 under acidic conditions
- slower loading of O2
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What is the Root effect?
- decreased capacity to bind O2 under acidic conditions
- may never reach 100% saturation
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Summary of secretion:
- gas gland tiss. anaerobic resp -- Hi levels of lactate and H -- decreased pH
- gas gland cells prod. CO2 combine with O2 -- carbonic acid -- lowers pH
- low pH triggers Bohr/Root -- hemoglobin releases O2 into blood
- Hi levels of plasma CO2 -- add. of CO2 into gas bladder
- blood leaves gas gland via rete -- diffusible gases build up
- pp of gas IN gg exceed pp in swb -- diffusion IN
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What are the 3 main problems of breathing in water?
- concentration
- density (800x) and viscousity (50x)
- solubility (decreases with increasing temp, salt/solutes)
- *warm water has less O2 than cold water, and salt water has less O2 than freshwater
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How do agnathans breathe?
- intake water through nostril
- ventilation pump (velum)
- 1-16 gill sacs with CC structure
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How do elasmobranchs breathe?
- intake through mouth and spiracle
- ventilation (ram - mouth; pump - mouth & spiracle)
- 5-7 ext. gill slits (gill arch and ray, gill rakers)
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How do teleosts breathe?
- intake via mouth
- ventilation (ram, pump)
- continuous one way flow (water across gill filaments)
- 4 gill arches with rakers
- CCE
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What can occur when oxygen needs increase?
- breathe more often
- take bigger gulps
- recruit more lamella
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What does it mean to "recruit more lamellae"?
- lamellae at tips rec. less water and blood flow
- with increasing water flow, tips get flow
- tips with more blood flow, higher blood pressure and dilation
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What are the costs of breathing?
- high density and viscousity = energy to ventilate!
- branchial pumping = 10-15% energy
- high vent volume = more costly
- in humans cost is 2%
- lower cost by ram breathing
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What is ram breathing?
- circumvents high cost of breathing when active
- transfers work of vent. to locomotory musc.
- seen in fishes in rapidly moving water
- or actively swimming ocean fishes
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What are the modifications/adaptations for fish who breathe air?
- mod. gills - thick lamellae
- mouth (vasc. buccal cav.)
- gas bladders and "lungs"(allow survival in drought!)
- cutaneous skin
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Describe the pump system (circulation)?
- 4-chambered, single pump heart
- sinus venosus (collects blood)
- atrium (initial pump)
- ventricle (main pump)
- bulbus/conus arteriosus (elastic/muscular reservoir)
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What is the general flow of blood in the circulatory system?
- deoxy blood pumped directly to gills via ventral aorta and afferent branchial arteries
- oxy blood from gills to body via efferent branchial art. and dorsal aorta
- through musc. and organs then to heart via cardinal veins
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How is oxygen transported?
- hemoglobin (O2 carrying protein)
- binds O2 at resp. surfaces, releases at tissues
- sensitive to pH (Bohr), Temp (lower affinity with increasing temp)
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What are two types of thermoregulation?
- ectothermy - reliant upon external heat
- endothermy - produce own heat
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What are the advantages of being an ectotherm?
low metabolic costs (less E, less food)
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What are the disadvantages of being an ectotherm?
cannot live/function well in extremes
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What are the advantages to being an endotherm?
- biochemical rxns become more efficient
- fish can utilize wider thermal ranges
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What are the disadvantages to being an endotherm?
high metabolic costs (req. more food, leaves less E for repro and growth)
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What are 3 ways to conserve heat?
- from rete near lg swimming musc
- from rete on liver
- CNS (circ. mod., special heat producing tissues)
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What are the behavioral ways to cope with temp fluctuations?
move to locations with better thermal environment
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What are the physiological ways to cope with temp. fluctuations?
- switch genes on/off
- increase enzyme concentration to compensate for reduced activity
- isozymes (diff. gene loci producing enzymes that operate at diff. temps)
- allozymes (alt. alleles at same locus that produce enzymes that operate at diff. temps)
- mod. at cell/tissue level (sat/unsat fat ratio, # mitochondria)
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What are the problems with high temperature evironments?
- structural degradation of proteins
- low O2 availability
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What are the problems with low temperature environments?
- slow biochemical rxns
- intracellular ice crystals
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What are the solutions to cold water env.?
- FW - not a prob -- stay below ice
- SW - supercooling (avoid crystal formation) or antifreeze (glycoproteins)
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Where is blood filtered in the kidneys?
glomerulus
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Where in the kidneys does resorption of ions take place?
tubules
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