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FISHES

FISHES. Phylum Chordata. Contains ALL fishes, amphibians, reptiles, birds, and mammals ALL chordates have a notochord; - a flexible rod that supports a chordates back (all embryonic, some retain, some change). CHARACTERISTICS. Cold blooded Paired Fins Gills, Scales EVOLUTION OF FISHES

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FISHES

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  1. FISHES

  2. Phylum Chordata • Contains ALL fishes, amphibians, reptiles, birds, and mammals • ALL chordates have a notochord; - a flexible rod that supports a chordates back (all embryonic, some retain, some change)

  3. CHARACTERISTICS • Cold blooded • Paired Fins • Gills, Scales EVOLUTION OF FISHES • Agnathans – jawless, 1st vertebrae, round mouth for sucking or filter feeding • Jaws (from gill arches) = Gnathostomes! & Paired fins improved swimming and feeding • Cartilage Skeletons (Sharks, Rays, Skates – still considered vertebrates) – Class Chondrichthyes • Bony Skeletons (Modern Fish) – Class Osteichthyes

  4. FORM & FUNCTION • Feeding • Everything you can imagine – carnivores (“big teeth”), herbivores (pharyngeal bone – small “teeth” on jaw, omnivores (random), detritivores (mouth on bottom), parasitic (“suckers”) • Respiration • Hard bony flap covering the gills - operculum • Air breathers • Obligate – must breathe air or will die (African Lungfish) • Facultative – whatever is convenient (some Catfish) • Usually found in tropical waters – because… • Circulation • Closed Circulatory System, Single Loop • Atrium --Ventricle -- Gills -- Body -- Back to Atrium

  5. Osmoregulation – balance of water levels in body • - Salt water fish tend to lose water & gain salt- Fresh water fish tend to gain water & lose salt- Homeostasis maintained by the kidneys • Brain Responses • - Cerebrum - thinking, voluntary activities- Cerebellum - coordination- Medulla Oblongata - functions of internal organs- Lateral Line System - senses vibrations • Movement • - Very muscular – make great swimmers and good food- Swim Bladder - buoyancy

  6. Reproduction • Oviparous (lays eggs) • Ovoviviparous (eggs stay in mom) • Viviparous (babies get nourishment from mom. Ex. Humans, cats, some fish)

  7. Classes of Fish • Class Myxini: “Jawless Fish” • EX: hagfish and lampreys • Class Chondreichthyes: “Cartilaginous fish” • EX: sharks, rays, chimaeras • Class Osteichthyes: “Bony Fish”

  8. Class Myxini (Mis-zini) • Hagfish and Lampreys • Slow enough metabolism that they can eat once every 6 months! (metabolism control) • They are scavengers (eat dead organisms) • Tie themselves into a knot to A) clean themselves, B) escape prey, C) pull on food Hagfish Lamprey’s oral disk Lamprey Hagfish knot

  9. Class: Chondrichthyes • Means “Cartilage fish” • Skeleton composed entirely of cartilage – still considered a vertebrate • Contains ALL sharks, stingrays, skates, and chimaeras • Characteristics: jaws, paired fins, skin covered w/ placoid scales (armored fish) • Denticles: teeth-like scales, feels like sandpaper

  10. 2 Subclasses Whale shark World’s Largest Fish • Elasmobranchs: Sharks and rays • Holocephalans: chimaeras (ratfish) Sand tiger Shark Manta Ray Blue Spotted Stingray Chimaera

  11. Class Osteichthyes • Means “bony fish” • About 25,000 spp. of bony fish • Characteristics: swim bladder, bony scales, and fin rays • 2 sub-classes of fish • Sarcopterygii: Lobefin fish • Actinopterygii: Ray-finned fish

  12. Sub-class: Sarcopterygii • Lobefin Fish; have round fleshy-lobes • EX: Coelacanth and Lungfish • Coelacanth: is over 400 million years old • Thought to be extinct; found in 1938 • Lungfish:Lives in Africa & South America • Facultative air breathers • Lungfish gave rise to land vertebrates • Can live out of water for short time periods Coelacanth Lungfish link Lungfish Lungfish walking!

  13. Sub-class: Actinopterygii • Ray-finned fish; most numerous group • Fusiform body shape: stream-lined allows fish to move through watch w/ great efficiency • Scale types • Ganoid: Thick bony scales that don’t overlap • Cycloid: Thin, smooth overlapping scales • Ctenoid: Thin, spiny overlapping scales Perch Lookdown

  14. Fins • ___________: on the top of fish used for stability • _________: tail fin used for locomotion & stability • ____________: bottom of fish used for stability • ___________: used for steering (anterior) • ____________: used for steering (posterior)

  15. Functions • Bony fish are Oviparious: (reproduce by laying eggs) • Air Bladder: gas-filled sac used to maintain buoyancy • Fish have a closed cardiovascular system • Lateral line system: canals on the side of the fish used to detect movement in the water

  16. Coloration Countershading • *Chromatophore: specialized cells that contain pigments • *Iridophore: crystals that produces a mirror-like silver color • *Countershading: camouflage where top of fish is dark, and bottom of fish is light, used to blend into the ocean Iridophore

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