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Dog fish integument:
identify: epidermis, dermis, scale, mucouse gland, and a chromatophore (pigment containing and light reflecting cells)
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Types of fish scales:
- Placoid scales (cartilagenous fish): tooth like structure containing a pulp cavity srrounded by dentine and capped by enamel (much like shark teeth and may have evoled from them)
- Ganoid scales(non teleost bony fishes): lower bony layer topped by enamel like material termed ganoine. thin scales interlock to form tough armour
- Cycloid and ctenoid scales (teleost bony fishes): thin layer of bone (no enamel, dentine or ganoine), so are light and flexible. allow for mobility and speed
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Support and locomotion:
- Varies tremendously
- Tuna have fusiform shape and are among the fastest swimmers
- Lumpsuckers have globiform shape and are poor swimming bottom dwellers
- fintypes and shape (size of caudal fin used for propolsion) also give some information
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Food Aquisition and Digestion
- Development of jaws are verry important to evolution
- gives more options for what is can eat - and how it captures and manipulates food
- jaws thought to have evolved from gill arches (seen in Chondrocythhes such as dog fish)
- Chondrocythe jaw problem - gap in corner of mouth for escape
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Gas Exchange and Water Balance: Respiration
- main processes: anaerobic glycolysis, and aerobic respiration
- evolved respiratory features: gills, lungs, cutaneous respiration
- Gills are delicate filamentous structures that are heavily vascularized (may be visible or hidden by gill covers)
- occur in primarily the cephalic region
- maximize seurface area for respiration
- sharks: gills are on interbranchial septa (septal gills) and tips of interbranchial septa acts as valves that can close external gill slits
- bony fish: gills covered by an operculum.
- large common opercal cavity for all gills
- inter branchial septa reduced so that primary gill lamellae extend freely into opercular caity (these are aseptal)
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Gas Exchange and Water Balance: Circulation
- heart: resposible for pumping blood through the system
- under autonomic control
- adjusts to match metabolic needs
- Fish: blood only passes through heart 1 time so only need 1 atrium and ventricle (also have sinus venosus, and bulbus arteriosus but are non contractible)
- considered either 2 or 4 chambered
- blood in capillary beds loses pressure. not a problem for fish as blood doesnt need to overcome large gravitational forces and they dont have large metabolic needs
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Gas Exchange and Water Balance: Excrition
- Fresh water Teleosts (perch): hyper osmotic (water in solutes out) excrete highly gilute urine and limit water intake
- Opisthonephric Kidney: eliminates excess water
- ammonia secreted through gills as special glands in gills absorb salt
- Marine teleosts: hypo osmotic (water out solutes in) drink water and excrete concentrated urine
- Sharks: convert ammonia to urea and retain it in their blood making them iso osmotic (high tolerance to urea). excrete excess salts via special rectal gland
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Sensory Abilities: Nervous system
- 3 components: central, peripheral, autonomic nervous systems
- parts of brain that are used more are larger and mor complex
- Bottom feeding fish: rely on smell to find food thus have large olfactory lobes and telencephalon
- Surface feeding fish: rely on sight to find food thus have large optic lobes and small olfactory apparatus
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Sensory Abilities: Sensory reception
- 4 sensor modalities: chemo, mechano, photo, and thermoreceptors
- Chemoreception: most primitive and in all animals
- salmon: can go from open sea to hatch site based off of dilute chemical trail
- Bony fish: have lateral lines (sense organ dectecting movement in fluid) seen running down the sid
- Sharks: some have modified lateral organ with electro receptors that can sense magnetic feilds
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Reproduction:
- Viviparous: (sharks, dogfish) embryos develope in female. needs a uterus
- Oviparous: (perch, most fish) embryo developes inside an egg. eggs laid and strewn across weeds
- Oviviparity: eggs retained in mother during development
- these a a reflection of environmental stresses affecting offspring survival
- External Fertilization: fertilization in external environment. pheremones used to attract mates. eggs laid in strategic locations (temperature predation water quality)
- Internal Fertilization: fertilization in female reproductive tract. these individuals developed elaborate neural and pheremonal mechanisms for facilitating copulations.
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propose an adaptive advantage of the heavily ossified skull
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perch are carniverous fish. how might hinged jaws aid in prey capture?
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Based on the size and shape of the teeth do you think the fish chews its prey or swallows it whole?
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how is the shape of the perch well adapted to minimize drag during swimming?
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which fins are involved with steering and which are involved with in propulsion? which fins would be used to slow the fish after a quick burst of speed? do any of the fins appear to have no obvious function?
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is your specimine male or female?
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what kind of scales do perch have?
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how are the gills of perch well suited to facilitate gas exchange?
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propose a function for the gill rakers
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how is the shark well adapted to minimize drag during swimming?
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which fins are involved with steering and which are involved in propolsion?
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what is the most likely function of the spiral valve in the intestine?
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is your specimen male or female?
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why are opercula considered and evolutionary advancement in the bony fish?
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the caudal fins of perch and dogfish sharks differ in shape. what effect might theis have on their swimming?
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what advantage do fish with swim bladders have?
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what features do you think might favor internal vs external fertilizations?
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how do the reproductive systems of the dog fish and perch differ? how does this relate to their mode of reproduction?
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which regions of the brain are relativley more and less developed? what does this say about abilities of perch and shark?(seeing smelling maneuvering orienting and reasoning)?
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Skeletal system of a bony fish:
- dermal exoskeleton and a bony endoskeleton
- hinged jaws
- teeth
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External Anatomy of a Bony Fish:
- nostrils:
- eyes:
- mouth
- opercula:
- dorsal, pelvic, pectoral, 2nd dorsal fin, anal, caudal fins:
- anus:
- urogenital opening:
- scale:
- lateral line:
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Internal Anatomy of a Bony Fish:
- Gills:
- Gill Filaments:
- gill rakers:
- liver:
- kidney:
- urniary bladder
- swim bladder
- pyloric ceca:
- spleen:
- stomach:
- intestines:
- gonads:
- heart:
- pericardial cavity:
- brain:
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