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What is a shoal?
groups of fish remaining together for social reasons
What is a school?
synchronized and polarized swimming groups
What 2 cues do fish use to school?
What are the 2 main structures of schools?
- shape depends on function
- usually a single species, can be mixed
What are the 4 advantages of schooling?
- hydrodynamic advantage
- avoiding predation
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
What are the costs to foraging in schools?
increased competition for food already found
What are the benefits of foraging in schools?
- faster location of food
- more time for feeding
What are the advantages of migrating in schools?
- more accurate homing of salmon
- culture transfer of information (juv. learn where to forage)
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
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
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
What are the 3 main types of migration (based on strategy)?
- wintering - climate factors
- spawning - gametic/larval factors
- feeding - trophic factors
What types of navigational cues to fishes use to migrate?
- olfactory - imprinting (common)
- sun compass
- geomagnetic/geoelectric fields
What is the primary purpose of swimming?
- avoid being eaten
- *very strong selective force
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
What is motion?
- a balance bw two hydrodynamic forces
- those that resist, and
- those that generate propulsion
What is resistance equal to?
inertia + drag
What is inertia?
energy req. to start something in motion
What is drag?
- force that acts backwards along the direction of motion
- -friction drag
- -pressure drag
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
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
How can drag be minimized?
- fusiform body shape
- tuck fins into folds in body
- vortex generators - stabilize boundary layer)
What 2 forces enhance propulsion?
What is lift?
force perpendicular for direction of motion
What is thrust?
linear force exerted by fish to propel itself
What are the 2 ways to generate thrust?
- undulatory (head to tail)
- oscillatory (side-to-side; paired and caudal fins)
What are the 2 components of normal force?
- side (lateral) - cxl when body/tail move back and forth
- thrust (fwd, along length of body)
How are contractions generated to create undulatory motion?
interaction bw skeleton (head/skull, vertebral columns, appendicular), muscles and fins
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)
What skeletal feature helps with braking and maneuverability?
appendicular skeleton - pelvic and pectoral girdles
What are the components of the pectoral fin/girdle?
- pect. fins attach at base of girdle
What are the components of the pelvic fin/girdle?
basipterygia attach pelvic fin to girdle (not to vert. column)
What are the 3 main muscle types?
- flexors - extensors (lateral musc)
- protractors - retractors
- adductors - abductors
What do flexors and extensors do?
lateral musc. along sides of body move vert. side to side
What do protractors and retractors do?
erect and depress doral and anal fin
What do adductor and abductors do?
move paired fins twds and away from body
How does cruising work?
- wave of contraction down length of body
- spinal nerves linked to myomere
- wave of innerv. contracts in sequence
How does acceleration work?
- all musc. on one side contract simultaneously
- Mauthner cells (giant axons) in teleosts
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)
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)
What are the 2 kinds of fins used in oscillatory swimming?
What are wing-like fins?
- thrust generated like a wing and generates lift
- ie. caudal fin of tuna
What are the advantages to a narrow caudal peduncle and wing-like fins?
- minimal drag, very efficient
- fast once started
What are the disadvantages of wing-like fins?
- poor quick start
- poor turning
- poor hovering
What are oar-like fins?
- use pectorals to scull like oars
- push water back (power stroke) and return collapsed fins horizontally
- -figure 8 motion
What are the 5 major fins?
What is the main function of the caudal fin?
propulsion (und, osc) and as vane/rudder
What is the main function of the dorsal and anal fin?
- propulsion (und)
- prevents roll
What is the main function of the pelvics?
- act as hydrofoils
- control pitch
What is the main function of the pectorals?
- propulsion (sculling)
- control yaw
- turning and brakes
What is the advantage to depth regulation (buoyancy)?
vertical structuring of food, predation, temperature, light, oxygen
What is depth regulation?
generating lift because fish will tend to sink
How do you generate lift?
- pectoral fins in sharks/tuna
- heterocercal tail of sharks
- hover via pectorals
What is the advantage to generating lift?
move freely up and down in the water column
What are the disadvantages to generating lift?
- high energy expenditure
- must maintain certain speed of movement
Who benefits most from generating lift?
How do you reduce dense materials for depth regulation?
- reduce calcification of bones
- reduce protein in muscles
- increase in water
What is the advantage to reducing dense materials?
lift doesn't very with depth
What is the disadvantage to reducing dense materials?
Who benefits most from reduction of dense materials?
deep sea fishes
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
What is the advantage to storing oils/fats for buoyancy?
lift doesn't vary with depth
What are the disadvantages to storing oils/fats for buoyancy?
- fine-tuning is difficult
- buoyancy regulation linked to metabolism
What is a gas bladder/swim bladder?
- gas-filled sac in upper part of body below vert. column and kidneys
- storage of gas
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
What are the disadvantages of a swimbladder?
- lift varies with depth
- large depth changes not practical over short time period
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)
What is Boyle's law?
- at a constant temperature, volume varies inversely with absolute pressure
- Pressure increases 1atm for every 10m in depth
What is the physostome solution for letting gas in/out?
secretion (gulp air) and burp
What is the disadvantage to the physostome solution?
fish dependent on surface if gulping air
What is the physoclistous solution for letting gas in/out?
resorption and secretion
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
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
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)
What is the Bohr effect?
- reduced affinity of O2 under acidic conditions
- slower loading of O2
What is the Root effect?
- decreased capacity to bind O2 under acidic conditions
- may never reach 100% saturation
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
What are the 3 main problems of breathing in water?
- 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
How do agnathans breathe?
- intake water through nostril
- ventilation pump (velum)
- 1-16 gill sacs with CC structure
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)
How do teleosts breathe?
- intake via mouth
- ventilation (ram, pump)
- continuous one way flow (water across gill filaments)
- 4 gill arches with rakers
What can occur when oxygen needs increase?
- breathe more often
- take bigger gulps
- recruit more lamella
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
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
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
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
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)
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
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)
What are two types of thermoregulation?
- ectothermy - reliant upon external heat
- endothermy - produce own heat
What are the advantages of being an ectotherm?
low metabolic costs (less E, less food)
What are the disadvantages of being an ectotherm?
cannot live/function well in extremes
What are the advantages to being an endotherm?
- biochemical rxns become more efficient
- fish can utilize wider thermal ranges
What are the disadvantages to being an endotherm?
high metabolic costs (req. more food, leaves less E for repro and growth)
What are 3 ways to conserve heat?
- from rete near lg swimming musc
- from rete on liver
- CNS (circ. mod., special heat producing tissues)
What are the behavioral ways to cope with temp fluctuations?
move to locations with better thermal environment
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)
What are the problems with high temperature evironments?
- structural degradation of proteins
- low O2 availability
What are the problems with low temperature environments?
- slow biochemical rxns
- intracellular ice crystals
What are the solutions to cold water env.?
- FW - not a prob -- stay below ice
- SW - supercooling (avoid crystal formation) or antifreeze (glycoproteins)
Where is blood filtered in the kidneys?
Where in the kidneys does resorption of ions take place?
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