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MARINE FISHES

MARINE FISHES. THE FIRST VERTEBRATES. Oldest and simplest vertebrates Most abundant vertebrates Three groups of fishes Jawless fishes Cartilaginous fishes (Chondrichthyes) Bony fishes (Osteichthyes)

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MARINE FISHES

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  1. MARINE FISHES THE FIRST VERTEBRATES

  2. Oldest and simplest vertebrates • Most abundant vertebrates • Three groups of fishes • Jawless fishes • Cartilaginous fishes (Chondrichthyes) • Bony fishes (Osteichthyes) • Yes, it is FISHES- the rule is fish is for a single individual or more than one individual of the same species • FISHES- refers to more than one species

  3. Jawless fishes • Class Agnatha • Around 30 known species • Includes hagfish & lampreys • Feed by suction with aid from teeth • No fins, & lack true vertebrae; no scales • Body is elongated and cylindrical • Most primitive fishes

  4. Cartilaginous Fishes • Class Chondrichthyes • Skeleton made of cartilage • Movable jaws • Mouth ventral • Underneath the head • Paired lateral fins • Sandpaper-like skin because of Placoid Scales • Includes sharks, rays, skates, and ratfishes

  5. SHARKS • ~350 living species • Caudal Fin is Heterocercal • Upper lobe longer than lower lobe • Fusiform, or spindle-shaped bodies • Five to seven gill slits • Powerful jaws with rows of teeth that are Continuously replaced • Carnivores & Filter Feeders • Found most often in warm coastal water Most only live in marine env. Some travel upstream

  6. SKATES AND RAYS • ~450-500 known species • Dorsoventrally flattened • Demersal: fish that live on the bottom • Five ventral gill slits • Stingrays • Whip-like tail with stinging spines • Electric Rays • Electric organs on each side of head • Skates lack the stinging tail

  7. Ratfish: AKA Chimaeras • ~30 known species • Only one pair of gill slits covered by a flap of skin • Long, rat-like tail

  8. www.itsallaboutfish.co.uk/ratfish.htm

  9. Bony Fishes • Class Osteichthyes • ~23,000 known species • Skeleton made of bone • Cycloid or Ctenoid Scales • Operculum: Gill Cover • Upper & lower tail fin same size: Homocercal

  10. Homocercal tail Cycloid scales

  11. BONY FISHES

  12. Fin Rays: thin membranes supported by bony spine • Anterior, terminal mouth • More flexible jaws with teeth attached to jawbone • Swim Bladder: gas-filled sac above stomach & intestines that helps in buoyancy

  13. BIOLOGY OF FISHES

  14. BODY SHAPE • ICHTHYOLOGY- study of fish • Body shape varies with habitat and lifestyle • Fast swimmers are streamlined- like tuna, marlins, mackerels, sharks

  15. Dorsoventrally flat- skates, rays and sea moths- demersal fish (live near bottom) Dragon sea moth Image from Liveaquaria.com

  16. Laterally flattened bottom dweller fish such as flounder, halibut and sole • Born with eyes on both sides of body but as they mature, one eye migrates to the dominant side

  17. Elongated bodies such as eels- live in narrow places amongst rock and coral reef

  18. Laterally compressed bodies live around coral reefs, kelp beds etc. Butterfly fish snappers

  19. COLORATION • CHROMATOPHORES-skin cells that contain pigments; irregular in shape with branches radiating out from the center of the cell • STRUCTURAL COLORS-Colors that result when light is reflected by a particular surface • Many times caused by IRIDOPHORES- chromatophores with light-reflecting crystals

  20. Colors reflect mood • warning coloration- coloration that allows organisms to escape from predators by advertising something harmful or distasteful video • cryptic coloration-color pattern that allows an organism to blend in its surroundings- video • Disruptive coloration- a color pattern that helps break the outline of an organism Ornate cowfish Disruptive coloration

  21. COUNTERSHADING- a color pattern that results in a dark back and a light belly- most common in epipelagic fishes (surface to 200 m)

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