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Published byJonathan Pitts Modified over 9 years ago
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Vertebrates: An Introduction
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Vertebrates: – Phylum Chordata Subphylum Vertebrata – Share 4 fundamental characteristics: Notochord – Backbone – vertebral column –spine – Dorsal row of hollow skeletal elements usually bone vertebra A single, dorsal, hollow nerve cord – Nerve cord – spinal cord – Protected by vertebrae – Ends in a complex brain that is protected by skull Gills or pharyngeal slits – Water passes over diffusing oxygen into body Post- anal tail
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Marine Fishes
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The term “ fish” is used for a single individual or for more than one individual of the same species The term “fishes” is used to refer to more than one species of fish Clown Fish Fishes
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Types of Fishes Study of fish is ichthyology
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Fish are the oldest, structurally simplest living vertebrates Most abundant – 15,300 are marine Ectotherms: – Cold blooded Fish are divided into 3 major groups: – Jawless fish – Bony fish – Cartilaginous fish
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Jawless Fish
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Jawless Fishes: – Most primitive – Class Agnatha – Lack jaws: Feed by suction with the aid of a round, muscular mouth Rows of teeth – Body is cylindrical and elongated – Lack paired fins and scales – Lack true vertebrae: Retain larval notochord as adults – 2 examples: Hagfish Lamprey
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Hagfish: – Slime eel: Produce slime as a defense mechanism Tie into knots – Feed on dead or dying fishes – Bore into their prey and eat from the inside out – Cold waters – 20 species are known – Length = 80cm (2.6ft) – Skin is used for manufacturing leather goods – Attack bait fish, fishing lines, nets and traps Hagfish Video
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Lamprey: – Mostly freshwater Breed in rivers and lakes but some move to sea as adults – Attach to other fishes and suck their blood Secretions in the lamprey’s mouth that prevents the victim’s blood from clotting Victims die from excessive blood loss or infection – 30 species Sea Lamprey – Great Lakes When Lampreys attack
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General Characteristics to all Fish Fins: – Movement Gills: – Breathing Scales: – 4 types: Placoid: Ctenoid Cycloid ganoid
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Scales Placoid: – Sharks and rays – Modified teeth covered by hard enamel – Grow with tips facing backwards – Used for protection – More scales added as fish grows Ganoid: – Gars and reedfish – Scales grow but not in concentric rings Cycloid: – Bony fish Soft & ray fish – Lungfish and bowfish – Scales grow with fish – Smooth posterior margin – circular Ctenoid: – Bony fish – Spiny-ray fish Perch – Scales grow with fish – Spiny posterior margin – circular
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Placoid scalesCtenoid scales Cycloid scales
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Bony Fish
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Majority of fishes = bony fish – Class Osteichthyes – Skeleton of bone – Have 2 types of scales: Cycloid: – Smooth, thin, flexible and overlapping Ctenoid: – Thin, flexible and overlapping with tiny spines along exposed border Skin is living & secretes protective mucous coating over scales – Mucous gives protection & reduces friction in water
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Sensitivity: – Lateral line organ: Contains cilia attached to sound receptors – When cilia vibrate, sound receptors sense this and fish responds – Nostrils (nares): Contain nerve receptors sensitive to chemicals in water – Eyes: On side of head in most species – Wide field of view
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Breathing: – Gills Located in the head region Covered by an operculum: – Flap of bony plates and tissues that protects gills – Also known as a gill cover How do gills work: – Water enters mouth and passes over gills – Oxygen diffuses from water through gill filament membranes and into blood – Carbon dioxide diffuses from blood into water and exits through gills slits
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Locomotion: – Swimming: Obtain food Escape from predators Find mates Some bony but mostly cartilaginous swim to flush their gills with water to obtain oxygen – Fins for movement: Paired fins: – Pectoral fins steering – Pelvic fins steering – These fins allow movement in all directions Single fins: – Can be soft or spiny – These fins are used for stabilization » Dorsal fins balance, upright » Anal fins balance » Caudal fin forward motion
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Pectoral Fin (2) Pelvic fin (2) Anal fin Caudal fin Dorsal fin - spiny
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– Speed of fish depends on : Body shape: – Fusiform (streamlined) = tapered body at both ends » Very little resistance » Fast swimmers » Ex: tuna, sharks, mackerels, marlins – Compressed = flattened from side to side allowing fish to turn easily and move quickly » Swim around corals, kelp beds, or rocky reefs » Burst of speed to escape enemies or capture food » Ex: snappers, wrasses, damselfishes, butterflyfishes
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– Depressed = flattened from top to bottom. » Adapted to live on the bottom » Lie on one side, with both eyes on top Begin life with one eye on each side, but as they develop one eye migrates up to lie next to the other one. » Ex: Flatfish – flounder, soles, halibuts – Elongated – long and thin » Live in narrow spaces in rocks or coral reefs, or among vegetation » Ex: moray eel, trumpetfishes, pipefish
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– Truncate = square short bodies » slow swimmers » Ex: trunkfishes – Globiform = round bodies » Slow swimmers » Ex: Porcupine fish Puffer Fish
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– Tail shapes: – Caudal fin height greater fin height and strength of muscle = faster fish Caudal fin: – Lobes of equal size = homocercal – Lobes of unequal size = heterocercal – Caudal peduncle: » Where the tail is attached to the body If narrow and the caudal fin is forked = fast swimmer
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Heterocercal and Forked = fast; Rounded and Pointed = slowest
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Mouth positions: – 3 types of mouth positions: Superior: – Upturned for feeding on the surface – Gather floating objects Terminal: – Forward facing position Inferior: – Under slung mouth – Bottom feeders – Variety of feeding methods Catfish video
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Buoyancy: – Swim bladder: Gas-filled organ that aids in buoyancy When muscles around swim bladder contract and shrink swim bladder fish sinks When muscles around swim bladder relax and allow swim bladder to expand fish rises
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Digestion and Transport: – 1-way digestive tract – Excretion: Metabolic wastes filtered by kidneys & excreted through urinary pore – Diffusion through gills – Nutrient transport: Via blood Nutrients diffuse into cells from blood
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Circulation: – All fishes have 2 chambered heart: Located below the gills Closed circulatory system Reproduction: – Usually separate sexes – Most have external fertilization and development Large numbers of eggs produced – Spawning release of gametes
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1)Lateral line 2) Muscle 3)Kidney 4) Spinal cord 5) Spine 6) Brain 7) Gills 8)Heart 9) Liver 10) Stomach 11)Intestines
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– Typical life cycle: Egg stage: – Spawning, fertilization, development, hatching Larval stage: – Plankton; drifts near surface Postlarval stage: – Active swimmers; muscles and fins continue to develop Juvenile stage: – Small adult Adulthood: – Capable of reproduction Salmon Spawning Video
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Adaptation of fish: – Camouflage: Changing color to match surroundings (ex: flounder) – Dark background pigments expand – Light background pigments contract Some species can camouflage selves in mottled pattern (ex: flounder) or shapes that match it surroundings (ex: sargassum fish )
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– Shapes and behaviors: Sea horses: – Wraps tail around objects to keep from being tossed up on beaches – Also suck up plankton and other food particles using long snout – Offspring develop inside pouch on male’s abdomen Flying fish: – Escapes predatory fish by beating caudal fin quickly (>40 beats/sec) to become airborne & then spreads pectoral fins to gain lift – Can “fly” up to 100 meters long and more than 10 meters above water Deep sea fish: – Often have large mouths with sharp teeth to help them catch any prey that become available – Many are bioluminescent and have luminescent lure dangling near mouth Seahorse video Flying Fish Video Barracuda jumping
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Swim Bladder Brain Gills Heart Stomach Gonads Intestine Liver Adipose fin
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Sharks and Rays
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Cartilaginous Fishes: – Class Chondrichthyes Sharks, rays, and skates – Skeleton made of cartilage: Flexible connective tissue made of protein Sharks: – > 250 species – Vary in size: 25cm pygmy shark 15+ meters = whale shark – Filter feeders Great white shark: – Dangerous to humans – Eat seals and sea lions Tiger and hammerhead killed humans in the past
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Great White Video
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Body structure: External Anatomy – Fast swimming – Fusiform body: Tapering from the rounded middle toward each end – Tail caudal fin Well developed and powerful Heterocercal – Upper lobe is longer than lower lobe – 2 dorsal fins 1 st larger and triangular – Paired pectoral fins – 5-7 gills slits: Visible on ventral side Used for breathing
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Bull Shark Video Tiger Shark
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– Spiracles: Dorsal side behind eyes Water enters and passes through gill chamber – Lateral line: Feel vibration – Acute sense of smell – Ampullae of Lorenzini: Pores containing nerve receptors in snout, which can detect electrical fields of other fish – Possess movable jaws Armed with teeth Bottom feeder dull, crushing teeth Predatory shark sharp, serrated teeth Several rows of teeth which move forward to replace lost teeth – 20,000 teeth in a lifetime – Paired lateral fins for efficient swimming: Constantly swimming or will sink – Need to pass water over gills – Rough, sandpaper-like skin placoid scales Backward facing teeth embedded in skin
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1) _____ 2) ______ 3) _______ 4) ________ 5) _________ 6) __________ 7) __________ 8) _______ Eye Gill slit Scales Dorsal Caudal Lateral line Pectoral Mouth
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Shark Whisperer
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Internal Anatomy: – Stomach: Inside have longitudinal ridges = expansion Have a cardiac stomach & pyloric stomach – Spiral intestine: Reabsorb nutrients Spiral = surface area – Liver: Big, gray, filled with oil responsible for buoyancy 2 large lobes; 1 small lobe = bile duct – Bile breaks down fats – Gallbladder: Under liver; stores bile – Pancreas: Digestive enzymes Under liver – Spleen: Blue Cleansing – Rectal gland: Small finger Osmoregulation of NaCl – Ovaries or testes: Reproduction glands
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Brain: – Olfactory sac: 2 large bulbous nerve sensors that detect chemicals in the surrounding water – Olfactory lobe: Area of the brain that receives nerve signals from the olfactory sacs and processes them – Cerebrum: 2 hemispheres between the olfactory lobes and are associated with sight and smell – Optic lobe: Large prominent lobes of the mid-brain that receives nerves from eyes – Cerebellum: Caudal from the optic lobe, it controls muscular coordination and position – Medulla oblongata: Base of brain, a widening of the spinal cord. Controls many spinal reflexes
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Heart: – Closed circulatory system – 2-chambered heart located below the gills Atria Ventricle – Small, gray oval shaped bulb right below the gills
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What is wrong with the diagram below? 2-chamber
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Reproduction in sharks: – Males have claspers: External Organ that transfers sperm to the females – Females lack claspers 3 ways to give birth: 1.Oviparous: Spawn eggs Embryo is enclosed by a large, leathery egg case (mermaid’s purse) that drops to the bottom after spawning 43% of cartilaginous fish use this method 2.Ovoviviparous: Females retain eggs inside her reproductive tract for additional protection Egg develops internally Gives birth to live young 3.Viviparous: Embryos absorb nutrients from the walls of the mother’s reproductive tract similar to mammals Live- bearers – No parental care Shark C-Section
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1)Nasal Cavity 2) Esophagus 3)Bile duct 4)Gall bladder 5)liver 6)stomach 7)pancreas 8) spleen 9) intestine 10)cloaca 11)Pelvic fin 12) Claspers = male
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Skates and Rays
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450-550spp Dorsoventrally flattened bodies Demersal fish live on bottom External anatomy: – 5 pairs of gill slits Underside of body – Pectoral fins are flat and expanded wings – Eyes on top of head – Mouth is ventral
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Rays Whip-like tails Stinging spines Live birth Examples: – Stingrays: Whip-like tail with stinging spines at the base for defense – Poison glands produce venom that can cause serious wounds to anyone who steps of falls on them Feed on clams, crabs, small fish Teeth modified into grinding plates that crush their prey – Electric rays: Special organs that produce electricity on each side of head Deliver shocks up to 200v Ancient Greeks used the shocks from these rays to cure headaches and other aliments – Original shock treatment Not all rays spend their life at bottom: – Eagle ray and manta ray – Devil ray: Fly through the water using pectoral fins as wings
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Skates Lack whip-like tail – Sturdier tails Lack stinging spines Lay eggs Some have electrical organs Extremely abundant Larger species are fished for in some parts of the world Skate swimming video
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