osteichthyes n.
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  1. Osteichthyes

  2. Osteichthyes • Means fish with bony skeletons • There are over 20,000 species of bony fish

  3. Where Do Most Fish Live? • Most fish live in the epipelagic zone

  4. Photic Zones in the Ocean

  5. Why do fish move? • To increase their chances of survival • To help them reproduce • To find food and shelter • To get oxygen • To migrate • To avoid predators Fish want to use as little energy as possible to get what they need

  6. What Slows Fish Down? • Frictional drag – the rubbing of the surface of a fish’s body against the water slows it down. • Ideal shape to reduce drag is a sphere

  7. What Slows Fish Down? 2nd Type of Drag • Form Drag – is caused by cross-sectional area pushing through viscous (THICK) water • To reduce form drag the fish should be like a long cylinder

  8. What Slows a Fish down?Type of drag 3 • Turbulance – caused by movement of the natural currents in the water. • The best shape to reduce this drag is like a torpedo, 4.5 times the objects diameter.

  9. Barracuda

  10. Types of Fins • Tail Fin (CAUDAL FIN) • Paired Fins (PECTORAL and PELVIC FINS) • Medial Fins (DORSA and ANAL FINS)

  11. External Anatomy of a Fish

  12. External Anatomy

  13. PRESSURE AND DEPTH • The weight of air pressing on an average adult person is about 8 tons. If this pressure were to be suddenly removed from us our blood would boil and we would die in seconds.

  14. How a Fish Swims • A fish swims by contracting the muscles on one side of its body like a wave along one side of its body going from head to foot.

  15. How a Fish Swims

  16. Caudal Fins • Caudal fins have different shapes • 1.   Homocercal --> Top and bottom halves the same size • a.       Rounded (Low A.R.) • b.      Truncate (Intermediate A.R.) • c.       Forked (Intermediate A.R.) • d.      Lunate (High A.R.) • 2.      Heterocercal --> Top half different size than bottom half

  17. Types of Caudal Fins

  18. Types of Caudal Fins • Heterocercal – often found on sharks

  19. Types of Caudal Fins • Some shapes help the fish swim fast like the lunate shape while others make the fish swim slow but turn well

  20. Paired Fins • Help the fish turn and stop

  21. Medial FinsDorsal and Anal Fins • Help prevent the fish from spinning and keep it stable in the water

  22. Measuring Fin Efficiency • Aspect Ratio = (fin height)2 / fin area Higher aspect ratio = faster fish

  23. Caudal FinsPush the fish forward

  24. Aspect Ratio and Fin Types

  25. Movement, Streamlining, and Speed • The speed limit of a fish is determined by the viscosity or thickness of the water • Streamlining of the fastest swimming fish (ex. Tuna) reduces turbulence • Eyes are flattened against the head and male sex organs are usually internal • Barracudas can reach speeds of 40 km/hr • Yellowfin Tuna can reach speeds of 45 km/hr • Larger Tuna can reach 110 km/hr

  26. Cruising Speed • Cruising speed for fish is about: • 1 or 2 body lengths per second (BL/sec.)

  27. Measuring Length

  28. Kinds of Muscle in Fast Swimming Fish • 75% of the total body mass of fast swimming fish like tuna is muscle • There is a greater percentage of red muscle than white muscle • Red muscle contains myoglobin, a pigment that attracts oxygen. • The power output of red muscle is 6 times that of white muscle

  29. Salmon

  30. Salmon Red Muscle

  31. Yellowfin Tuna

  32. Barracuda

  33. Flounder

  34. Flounder Muscle

  35. Water Viscosity • Water viscosity is the thickness of water caused by the sticky cohesion of water molecules to each other and the adhesion of water molecules to other objects causing friction. • Cold water creates 2x as much friction as warm water. • An organism in warm water must be smaller than a same shaped organism in cold water to prevent sinking due to viscosity

  36. Water Viscosity

  37. Fish Senses • Sight – some fish can see color and can see in very dim light • Hearing – fish can hear • Smell – fish have nostrils used for smelling • Touch – fish can feel objects against their skin • Lateral line- A system of canals on the sides of fishes that helps fish detect changes in pressure, vibrations and currents

  38. Fish Eyes

  39. Fish Hearing

  40. Fish Smell

  41. Lateral Line

  42. Lateral Line

  43. Lateral Line

  44. Lateral Line

  45. Lateral Line • Fish “hear” via their lateral lines, a line of pressure sensors running along each side of the fish that pick up pressure waves (= sound) in water. When someone pounds on an aquarium, that creates waves of pressure in the water that, to the fish, would be analogous to cupping your hands and pounding on your ears--NEVER POUND ON A FISH TANK!

  46. Functions of the Lateral Line • Detect changes in pressure and vibrations and currents • Detect prey • Swim together in a school • Detect predators on the side or behind them • Pick up vibrations from the swimming together of other animals


  48. BUOYANCY • Ways animals and plants avoid sinking • By adjusting body density to the same density as that of the water around them (neutral buoyancy). • Having flattened or bristly shapes that increase surface area and reduce sinking.