Is a seahorse a fish, amphibian, or reptile? FISH

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1 Ch. 30 Loulousis

2 Is a seahorse a fish, amphibian, or reptile? FISH

3 Vertebral Column (Endoskeleton) Gills Single-loop circulation Kidneys Also share all the characteristics of chordates such as notochord, bilateral symmetry, coelomate, sense organs

4 Structures to help swim and sense environment: Endoskeletons Fins Swim bladders Lateral lines Shape Muscular tail

5 Most fish have complete endoskeleton made of cartilage or bone Muscles attach for movement Fins are attached

6 Increase stability Some have paired fins to help turn, dive or climb Paired fins evolved into limbs and wings Swim bladder Amount of gas regulates vertical position in water Sharks and stingrays don t have swim bladders, use fat for buoyancy

7 Hard bony plates formed from skin Can be tooth-like, diamond shaped, cone shaped, or round Some fish (catfish) do not have scales Shark scales are like teeth of other species Annual growth rings in scales for some species can tell you age

8 Eyes Nostrils Lips Fins Skin Inner ears Lateral line System of small canals in the skin, senses water vibrations by currents or pressure waves Directs their swim movements

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10 Fish get oxygen for cellular respiration from water Gill- respiratory organ, made of rows of filaments Located at the gill slit- rear of cheek Use countercurrent flow to extract maximum amounts of oxygen Single-loop blood circulation

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12 Water passes over gills in one direction and blood flows in the other direction Allows oxygen to diffuse into the blood in gill capillaries Gills are efficient and extract up to 85% of the dissolved oxygen in the water

13 Blood leaves gills capillaries -> vessels in fish body -> heart Heart is a simple chamber pump, one atrium, one ventricle

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15 What is the major respiratory organ of a fish? Gill (made up of gill filaments) Why does a fish open and close its mouth as it swims? Movement pumps large amount of water over the gills and drives countercurrent flow How does countercurrent flow increase the efficiency of a bony fish s gills? Water passes in one direction over capillaries while blood flows in opposite direction. Allows oxygen to diffuse into the blood over the entire length of the capillaries.

16 Osmosis: causes net movement of water through membranes (like gills and skin) toward regions of higher ion concentration (less water) Most vertebrates body is 2/3 water Sea water has 3x the amount of ions than a fish body

17 Marine Fish Lose water to environment through osmosis Fish must drink sea water and pump out excess ions through their gills Fresh Water Fish Bodies have more ions than surrounding water, so tend to take in water through osmosis

18 Filter water and waste from the blood Excrete products as urine Regulate concentration of substances in blood Marine Fish Conserve water excrete small amount of urine (or waste) Freshwater Fish Excrete most of their waste as urine, very little out gills

19 Kidneys are organs made up of nephrons Tubelike organs made up of thousands of nephrons Regulate the body s salt and water balance and remove metabolic wastes from the blood Excess water and bodily wastes leave the kidneys in the form of urine Marine fishes excrete small amounts of urine and rid their bodies of ammonia largely through their gills Freshwater fishes excrete large amounts of dilute urine

20 Most reproduce sexually External fertilization Spawning Male and female release gametes into water and eggs are fertilized Group spawning- Large number of eggs ensures some will survive Sharks, skates, and rays have internal fertilization produces larger offspring, less likely to be eaten

21 Why is maintaining water balance within the body a different process for freshwater versus marine fishes? How is group spawning advantageous to fish?

22 1.Identify chambers A and B. 2.What is the function of chamber A? B? 3. Where does blood that enters chamber A come from? 4.Where does blood go when it leaves chamber B? 5.How do the walls of chamber B enable it o carry out its function?

23 3 classes 1.) Agnatha- Jawless fish 2.) Chondrichthyescartilaginous fish 3.) Osteichthyesbony fish

24 Hagfishes and lampreys Have cartilage skeletons Strong fibrous connective tissue Notochord in adulthood Only modern vertebrates without a backbone! Swim with undulating movements

25 Hagfish are scavengers and predators Eats dead body of animals on ocean floor Lampreys are parasitic Uses circular suction-cuplike mouth to suck blood of host

26 Sharks, skates, rays, and ratfishes Paired fins and jaws Jaws let animals grasp and crush prey Cartilage skeletons strengthened By calcium carbonate

27 Living fossils- having changed little in hundreds of thousands of years All are predators Has triangular-shaped scales makes skin rough Shark teeth are modified scales also triangular arranged in 6-10 rows System of tooth replacement ensures the teeth in use are always sharp and new

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29 Have flat bodies adapted for sea floor life Rays are less than 1m long and skates are smaller

30 Class osteichthyes Most numerous of all fishes Have a skeleton made of bone and paired fins Have teeth that are fixed onto the upper jaw Have structural adaptations: Lateral lines Opercula Swim bladders

31 Lateral line system (1) Sensory system that extends along each side of a bony fish s body Enables a fish to detect motionless objects by the movement of water deflected by that object Helps a fish perceive its position in water Occurs by nerve impulses from ciliated sensory cells Much like we hear music with our inner ear Both use sensory cells with cilia to detect vibrations

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33 Gill Cover (2) Operculum hard plate that covers the gills on each side of the head Movement of the opercula and other muscles permit a fish to draw water over the gills, which allows them to take in oxygen Can move water over their gills while remaining stationary Doesn t have to swim to respire Enables them to conserve energy

34 Swim Bladder (3) Keeps a fish from sinking Swim bladder is a special gas sac By adjusting gas content of swim bladder, fish can regulate their buoyancy As it fills, they rise and vice versa Early bony fish had swim bladder connected to throat Gulped air to fill it Modern bony fish swim bladder does not have a direct passageway to mouth Gas is exchanged between bloodstream and the swim bladder

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36 **There are 2 groups of bony fishes Ray-finned fishes Yellow perch Lobe-finned fishes coelacanth

37 Vast majority of living fishes Fins are supported by bony structures called rays Teleosts most advanced of the ray-finned bony fishes Highly mobile fins Very thin scales Completely symmetrical tails Includes 95% of all living fish species

38 Only 7 species survive today 1 species is coelacanth Other 6 are all lungfishes Have paired fins Each fine consists of a long, fleshly, muscular structure supported by central core of bones Bones are connected by joints like joints in the bones of your hand Bony rays are only found at the tips of each lobed fin Scientists are still debating ancestry.. Used to believe ancestor was amphibian Now they believe it is most likely a third type of lobefinned fish now extinct

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