Study Guide for Ichthyology Midterm 2
Study Guide for Ichthyology Midterm 2 BIOE 127 - 01
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This 10 page Study Guide was uploaded by Jim Freed on Saturday November 7, 2015. The Study Guide belongs to BIOE 127 - 01 at a university taught by Bernardi,G. in Fall 2015. Since its upload, it has received 204 views.
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Date Created: 11/07/15
Midterm 2 – BIOE 127 Icthyology Form & Function Body Form - Paired fins = pectoral and pelvic Fins used to control movement in 3-D space -Unpaired fins = dorsal, anal, caudal Bodies Elongate: eel-like, long and slender Deep: very tall (depth) and thin (compressed) Fusiform: energetic advantage, bass-like Depressed: flat body (skates/rays) Subcircular: round, hemispherical Ovale: truncated, good to deter predation Tails Most important circled Mouth Terminal mouth = equal, mouth positioned on anterior end and specialized for the most diverse feeding Superior mouth = mouth positioned on the dorsal side of head, bottom jaw protrudes more Inferior/Sucker = mouth positioned on the ventral side of head for grazing Teeth & Gill Rakers: reflected by the diet! large prey = small rakers intermediate prey = medium rakers; rakes food and keeps small food inside mouth using rakes small prey or filter feeder = large rakers, very long and thin, comb-like, does not let food through gills Feeding Ram = gill arches not joined and no membrane is present Suction allows for water to flow through when travelling fast Ram Suction = gill arches joined by membrane (isthmus) and used to suck food/water into buccal cavity. Water is then pumped out gill openings Cirri = fleshy flaps for camouflage and chemoreceptors Movement Three types: Pitch (pectoral/pelvic) (dorsal/aRoll Yaw (all fins) Preadaptations = trait evolved because it served one particular job but subsequently served to do another job; increases fitness Examples: Gurnards (sea robins) – pectoral fin rays modified for touch and taste Flying fish – pectoral fins help change pitch while above the water in the air Sharks – pelvic fins help with internal fertilization Clingfish – pelvic and pectoral fins are fused to from very strong suction disk Thresher shark – caudal fin with very long upper lobe is used to whip and stun prey Flying fish – caudal fin with long lower lobe helps with beating the water when "flying" Surfperch – anal fin has flap in females and hook in males to latch on to deposit sperm inside females Remora – dorsal fin modified into suction disk allows to hitch rides and eat food scraps of large fish Triggerfish – second dorsal spine locks the first spine into place inhibiting a predator from eating it Anglerfish – dorsal fin highly modified with an ilicium (lure) with esca (bait) Sawfish – rostrum elongated helps sensing organisms hidden beneath a layer of sediment Swimming Efficiency Strouhal Number = product of the frequency of tail flapping and the jet's width, divided by the fish's speed - #'s between 0.25 and 0.35 = efficient swimmer Placoid, ganoid, and cycloid scales improve efficiency in Weight (3.37 Nm) hydrodynamics by reducing drag Thrust (3.37 Nm) Swimming Modes (10.58 Nm) Drag Thrust (11.12 Nm) Medial (6.96 Nm per fin) Lift (3.24 Nm) Swimming Type 1) Carrangiform = predominantly tail driven, stiff body 2) Labriform = pectoral fins mainly used, caudal fin acts as a rudder 3) Anguilliform = eel-like, snake like movements 4) Ostraciform = body encased in stiff shell skeleton and other fins do most of the maneuverability Physiology Buoyancy = maintaining vertical position in the water column -potentially energetically costly -many primitive fishes had lungs; but many advanced lineages lost the respiratory function t o become… -gas bladder = used to regulate buoyancy and sound production/detection in some fish controlled by changing the size of the gas bladder -respiratory gas bladder = gut connection; fish must gulp air to maintain buoyancy; highly vascularized and subdivided and adapted for gas exchange -Two types of gas bladders: 1) Physostomous gas bladder = primitive sac, out-pocket from gut, vascularized, connected via pneumatic duct; fine control difficult 2)Physoclistous gas bladder = more derived teleost have this gas bladder that is sealed off from gut—gas enters via blood from the gas gland and oval, excess gas is offloaded via the gills -gas gland = inflates gas bladder by diffusion -rete mirabile = "wonderful net", looping bundle of capillaries that generates a concentration gradient -oval/pneumatic duct = removes gas and directs gas from esophagus into gas bladder To liver Rete Oval mirabile Gas gland (gas production) (gas secretion) To heart To heart Gas space Gas space To liver Esophagus Rete Gas gland Pneumatic duct mirabile (gas secretion) Physostomous Gas bladder Physoclistous Gas bladder -The pneumatic duct permits gas release via the esophagus in a physostome, whereas a physoclist must rely on a specialized area of the bladder wall for gas respiration. Both have gas glands and associated rete for gas addition -Bohr effect = hemoglobin's affinity for oxygen is inversely related to acidity and CO2concentration due to the… -Root effect = hemoglobin dumps oxygen quickly in an acidic environment but rebinds oxygen relatively slowly when pH increases How are the a) physoclistous air bladder and the b) physostomas air bladder filled? a) Inflated actively and deflated passively b) gulping air at the surface to inflate and burp air out via pneumatic duct to deflate -Chemical buoyancy = lipids/fats -Elasmobranchs; 20-30% of body weight is from high density/fatty livers; noncompressible, great for changing depths quickly; energetically costly to produce and can be metabolized during starvation periods -Nototheniidae: pelagic/benthic Antarctic icefishes; lack gas bladder like ancestor, high proportion of skeleton is cartilaginous; store lipids throughout body in muscles and blubber layer Respiration Things to consider: -water contains considerably less oxygen (~1% compared to air that is ~21%) -saltwater holds 25% less oxygen than freshwater due to lower solubility as a result of high salt concentration -oxygen is lowest in warm, marine environments, highest in cold, freshwater environments -water requires more energy to move through and to pull oxygen from due to high density and viscosity Suction Respiration =fish not using much O a2d actively pumping water through mouth and out gills Ram Respiration =fish swims fast to force water to flow over gills Opercular chamber expanding (negative Gills pressure) -very efficient at extracting oxygen from water due to high surface area and countercurrent exchange Aerial Respiration -has arisen at least 38 times since first evolving 400 mya and has allowed successful colonization of land (tetrapods) - over 370 fish species breath air -Amphibious fishes: have a well supported gill structure to prevent collapse, percolate water inside buccal & opercular cavities, and skin is often scaleless and well vascularized for gas exchange -Labyrinthine plates = highly vascularized chamber that can hold air and allows for gas exchange -Facultative air breather = supplements respiratory needs with gulping air at the surface (i.e. Australian lungfish) -Obligate air breather = requires access to air to sufficiently exchange gases (i.e. S. American lungfish) Circulation Conus arteriosus Conus arteriosus is an extremely elastic, multi-valve chamber to reduce backflow of blood into heart but not completely sealed; in teleosts it is replaced by bulbus arteriosus, which is a nonmuscular chamber that reduces the pressure oscillations from heartbeat and provides continuous blood flow and no backflow occurs Thermal Regulation Typical Fish Tuna Endothermic Fishes -generally tend to be large fish that swims a lot, has large muscles that can produce and also retain heat -modified circulatory system with countercurrent exchange to retain heat ("rete") -eye muscles generate heat also which allows for greater sensitivity/awareness Osmoregulation Freshwater: -little salt outside, lots of salt inside -lots of pee & ammonium (and feces), high in salt -does not drink water -chloride cells help take up salt from water -hyperosmotic to environment; gain water through gills/skin, lose solutes by diffusion across gills, actively transport salt back into blood to produce lots of dilute pee Saltwater: -lots of salt outside, less salt inside -lose water via gills, must constantly drink water -less pee with high salt and ammonia concentration Chondricthyes: -super salty body, more than ocean -water goes in, pees a lot -sodium removed in chloride cells and rectal glands -use urea to store the buildup of toxic Nitrogen Feeding Strategies in Teleost Fish Feeding takes place in a very difficult medium -low oxygen, high viscosity/density As a result, fish have developed the most highly kinetic skull (more than 20 movable bones!) Suction Feeding = first observed in hagfish (raspers) but first true suction is seen in sharks Occurs via expansion of the throat and mouth, which creates negative pressure inside buccal cavity and when mouth opens, water/food is pulled in passively Hydrodynamics of Suction Feeding -Flow = symmetrical due to symmetrically round mouth -Velocity decreases at half the mouth diameter away from the mouth (greater than that = less useful) -Fluid speed only significant within one mouth diameter -larger gape = less suction (think vacuum hoses; wide hose = less suction; thin hose = strong suction -gape distance is proportional to peak fluid velocity Fluid Mechanics Why would jaw protrusion evolve? Body 1) Sneak up on prey Ram 2) Increase force exerted on prey for greater capture success. -Research shows that suction feeding accelerates water around the Suction prey and as a result, increases total force on attached, escaping, and free floating prey by up to 35% Pure-ram = feed by simply swimming fast with mouth open (i.e. anchovies) Ram-biting = use teeth to snag/restrain prey while suctioning/swimming fast Jaw Jaws: act on a 3order lever, where force and lever are on the same side Ram -ratio close to 0 = velocity modified but not strong (i.e. needle fish) -ratio close to 1=force modified, not fluid dynamic(i.e. reef fish) Pure Biting Ram Functional Roles of Suction 1) Respiration = slow suction 2) Prey Capture = capturing 3) Prey Transport = swallowing Prey Transport Mouth > Brachial Arches > Esophagus -4 and 5 brachial arch is usually modified into bony plates, which make up the pharyngeal jaws -Pharyngeal jaws work using highly modified muscle arrangements for macerating, processing, and transporting prey -Pharyngeal diversity: 2 morphs in one species! A) Papilliform = plant shredding B) Molariform = shell crushing -Pharyngeal transport: uses various muscles to manipulate prey; also uses inertial transport (i.e. eels) as seen with reptiles Reproduction & Growth Sex Determination -Sex chromosomes: -rarely seen in fish; -heterogametic (flexible) gender can be either sex; -polygenic = all over genome -sex determination depends on hormones present; same species male/female can have same heterogametic sex chromosomes -Environmental Sex Determination (ESD): -sex is determined by temperature -In Atlantic silverside (Menidia menidia) the northern population has a limited spawning season and exhibit genetic determination while the southern population has a longer spawning season, it is more sexually labile i.e. anemonefish -Larvae spawned in summer tend to become males -Larvae spawned in spring @ low temp tend to become females -longer growth period; take advantage of the size to egg ratio -Gonochoristic = sex determined at early age and fixed (majority of fishes) -Hermaphrodites = have both male and female sex organs -Sequential: 2 types 1) Protandrous = functional male > functional female 2) Protogynous = functional female > functional male (common) i.e. sheephead -Simultaneous = produces viable sperm and eggs simultaneously >Why change sex? -Increased fitness! -change sex when, at a given size, the reproductive success of the other gender becomes higher -females limited by number of gametes (eggs) produces, males limited by number of matings -Sex-change theory predicts it is best to be male when small and female when large also depends on ecology! (i.e. clownfish larvae lands on anemone and becomes male, if no other individuals are present it will become a female and wait for next larvae, which will be male) -Unisexual Species: i.e. Amazon mollies, (Poeciliopsis spp.) -does not allow for the removal of harmful mutations -as fitness decreases over generations, species will turn to sexual reproduction to clean up the bad mutation Sexual Selection -Selection to increase mating success -May serve no other advantage than mating and may actually handicap its possessor with respect to other fitness traits -Involves one fitness component Fitness = Viability + Fecundity + Longevity + Mating Success -Driving force behind sexual selection: -Males = limited by # of females to mate with -Females = limited by # of eggs and/or pregnancies -Females are typically choosy since eggs are expensive vs. cheap sperm -Intersexual Competition (i.e. Swordtails, Poeciliidae) -Females prefer longer tails (Sensory bias = females have genetic preference for longer tails) -Even seen in primitive fish when artificial tail was attached -Lengthy tails are costly; length balanced by cost of decreased predator evasion vs. benefit of mating success -Fish that switch roles are opposite—i.e. seahorses, pipefish: males are choosey since they foster the eggs/young and will actually take up eggs from multiple female (common for females in fishes when roles are normal) Morphology Fertilization (fusion of male and female gametes) -External = mass spawning events that release sperm/egg into current to fertilize and settle elsewhere -Internal = occurs inside fish and requires intermittent organ for depositing sperm (i.e. claspers, gonopodium) Embryonic Development Categories based on where development occurs and whether embryo depends on yolk or maternal mother -Oviparous = lay eggs, ~98% bony fish, ~40% chondricthyes -Viviparous = live birth, ~2% bony fish, ~10% chondricthyes -Ovoviviparous egg hatches internally then live birth, rare in bony fish(i.e. rockfish, sculpin), ~50% chondricthyes Reproductive Behavior -Parental care = some form of defense or manipulation of eggs or young (i.e. mouth brooders) -90 families include species that provide care -31 % biparental, 69% uniparental (male = most common caregiver) -External fertilization: 89%; 90% of those are cared for by the male -Internal fertilization: 11%; 86% of those are cared for by the female -Male care likely evolved to insure no other ales would fertilize the eggs -smaller clutch size = more care Growth Two general traits shared by most fish that set them apart from other vertebrates = larval stage & indeterminate growth -Aging fish: use scales, otoliths, spines, vertebrae, and tetracycline Sagittal Otolith -used for aging and life history studies since chemistry of accreted layer reflects water chemistry of that time (i.e. settlement marks = change in ring growth pattern due to change in diet/environmental factors) -characteristic of species -daily deposit of calcium carbonate that create one ring (lamellae)for each day lived, as lamellae grow, days are compressed and able to count years using annulus Scales -same concept of ototlith, where each rings reflect a period of time and can indicate life history events, however scales are easily lost and regrown, thus not as accurate/reliable Vertebrae -useful for dating elasmobranchs, which have no bony parts and do not add layers to their skull Perception Hearing -Rings filled with gels of different densities that allow diff. frequency of sounds penetrate deeper into the ear bones to put pressure on nerves that attach to the otolith. -Weberian apparatus amplify sounds -Some fish can also produce sounds by cracking pectoral fins, grinding pharyngeal jaws, or even banging muscles against the swim bladder Smell -passive -large scent organ relative to brain size -what the fish smell are the amino acids of other animals -fish are most sensitive to certain amino acids that are present on its own skin so it can tell when it is nearby its own species, breeding ground, or if an predator is near -can also create "scents": Schreckstoff, which is useful when visibility is poor Vision -relatively poor vision: easily confused by mimics and ocelos (false eye) -Lake Victoria: run-off makes lake more turbid and harder to see vibrant colors -lead to hybridization of species and decreases diversity -Vision experiments lead to the discovery that fish can see different shapes, letters, colors, as well as UV and polarized light -however due to the harmful effects, larger fish cannot see UV -Dichromate = 2 cones = luminance component (brightness) & chromatic component (color) Lateral Line -Sensory system made up of ducts that detect vibrations and pressure changes in the surrounding environment -surprisingly, not commonly found in schooling fish due the overload of senses it would cause (???) Electroreception -electric organs that help gather information about the surrounding nearby enviro. -used to prey on fish by stunning prey -used in communication, with some species as mating calls -ex: Torpedo rays have special muscles that actually give off electricity rather Elasmobranchs use electromagnetic reception via Ampullae of Lorenzini Touch & Taste -modified fin rays allow the sea robin to taste/feel what lies in or beneath the sediment Fish Behavior Behavioral ecology: animals behave in ways that maximize their fitness -reproductive behavior = more successful offspring -feeding behavior = maximum energy gain for healthier gametes and ability to provide for offspring Competing for Resources 1) Evolutionary Stable Strategy = very stable behavior that is difficult to invade/change -can be changed by environmental change -Evolutionary game theory = a strategy that cannot be invaded -Tit for tat (get what you give) -chess (individuals try to overcome each other) -monopoly (individuals talk, negotiate, compromise for benefit) -rock/paper/scissors (different options with different advantages/disadvantages) 2) Resource Defense = the benefits of the resources outweigh the costs (injury, expenditure) of defending them 3) Ideal Free Distribution = amount of resources is proportional to the size of the population and distribution of populations is proportional to the amount of available resources 4) Mating Strategies & Tactics -mating in aggregations vs. groups vs. pairs -guarding territory of resource ( i.e. Daccylus reticulatus protects certain area of resources just large enough that female cannot swim far enough to find more, trapping her Sexual Selection 1. Mate choice by resources (i.e. nest size, food, protection, etc.) 2. Mate choice by genes (strong female choice, i.e. swordtails with long sword =good, thus other genes must be good too) -Good Gene Hypothesis Sexual Conflict -eggs are limited, sperm is cheap (generally) -females usually choosey(reversal in seahorses) Parental Care & Family Conflicts 1. (See Parental Care section on Page 8) -Hermaphrodites (see section on Page 7) why change sex? = increase fitness! Certain sex has higher fitness at different times 2. Familial Conflicts -kin selection = selecting kin that is related (i.e. Brachardi's Cichlid: not many individuals mate but when they do the clutch says close, once grown, juveniles help protect the next clutch/kin, and so on so they are long surviving) -brood parasitism = babies of different species hang around parent of another species and gets raised by that foreign mother unknowingly by the fish since it had been raised since an egg Mating Systems -Influenced by two factors: 1) Ability/accessibility to mate 2) parental desertion -Many Systems (i.e. monogamy, polygamy, polyandry, promiscuity -multiple paternity = one male, many females/one female, many males getting it on ( i.e. surfperch, kelp greenling) Communication and Signaling -Honest signals = if animal is dangerous, it will show special markings (aposematic coloration) -Dishonest signal = if animal is dangerous but disguises as not dangerous or if animal looks dangerous but is actually not -Mimicry: 1) Batesian = mimic is not really dangerous 2) Mullerian = mimic is toxic as well Genetic vs. Environmental Factors -Nature vs. nurture, due part to enviro. pressures and variability and part to genes that are also influenced by enviro. -Innate behavior = less subject to environment variation because it is developmentally fixed -Fixed action pattern = organism will carry out behavior no matter how dangerous, inappropriate simply because the behaviors are important to increase survival fitness in the long run (i.e. three spined stickleback will attack other males with red bellies so in reality it will attach anything with red coloration on the bottom) -happens with brood parasitism Symbiosis -Fish-Fish = i.e. trumpetfish (carnivore) hide on herbivores and eat prey when they are not looking -Fish-Invertebrates = i.e. clownfish and anemone -Fish-Other vertebrates = i.e. blood suckers, or fish that go up urethra
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