Osteichthyes

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Osteichthyes
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Osteichthyes

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

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Where Do Most Fish Live?

• Most fish live in the epipelagic zone

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Photic Zones in the Ocean
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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

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What Slows Fish Down?

• Frictional drag the rubbing of the surface of a
  fishs body against the water slows it down.
• Ideal shape to reduce drag is a sphere

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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

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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.

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Barracuda
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Types of Fins

1. Tail Fin (CAUDAL FIN)
2. Paired Fins (PECTORAL and PELVIC FINS)
3. Medial Fins (DORSA and ANAL FINS)

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External Anatomy of a Fish
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External Anatomy
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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.

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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.

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How a Fish Swims
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Caudal Fins

• Caudal fins have different shapes

1.   Homocercal --gt 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 --gt Top half different
size than bottom half
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Types of Caudal Fins
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Types of Caudal Fins

• Heterocercal often found on sharks

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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

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Paired Fins

• Help the fish turn and stop

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Medial FinsDorsal and Anal Fins

• Help prevent the fish from spinning and keep it
  stable in the water

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Measuring Fin Efficiency

• Aspect Ratio (fin height)2 / fin area Higher
  aspect ratio faster fish

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Caudal FinsPush the fish forward
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Aspect Ratio and Fin Types
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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

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Cruising Speed

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

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Measuring Length
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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

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Salmon
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Salmon Red Muscle
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Yellowfin Tuna
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Barracuda
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Flounder
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Flounder Muscle
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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

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Water Viscosity
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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

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Fish Eyes
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Fish Hearing
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Fish Smell
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Lateral Line
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Lateral Line
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Lateral Line
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Lateral Line
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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!

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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

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BUOYANCY
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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.

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Maintaining Buoyancy

• To maintain buoyancy the fish will either
• Adjust the density of its body by using a SWIM
  BLADDER
• They will adjust the density of the components of
  their insides (they will consume lighter weight
  ions and leave the heavier ones in the
  surrounding water)

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SWIM BLADDERS

• A swim bladder is a balloon-like structure that
  is
• inflated to make the fish rise higher in the
  water
• or deflated to make the fish sink lower

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SWIM BLADDER
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SWIM BLADDER

• CLOSED

• OPEN

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No Swim Bladder

• Some fish like Tuna do not have a swim bladder
  and must swim fast to prevent sinking
• Some fish like catfish do not have a swim bladder
  and spend their life on the bottom

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Respiration

• Fish use gills to absorb oxygen from the
  surrounding water

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Comparison of Gas in Ocean Water and the
Atmosphere

• Undissolved

Gas Chemical Symbol Percentage in
Air Percentage in Sea Water Nitrogen N 2
78.08 62.6 Oxygen O 2
20.95 34.3 Carbon Dioxide CO 2
0.033 1.4 Dissolved Oxygen
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Dissolved Gases

• Gas Ocean Atmosphere
• Oxygen 5-10ml/L 200ml/L
• Dissolved gases vary in water with temperature
  and salinity.
• Cold fresh water can hold more dissolved gas than
  warm saltwater.

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Parts of a Gill

• Gill Arch - stiff structure that supports the
  gill filaments and the gill rakers
• Gill Rakers prevent food from clogging up the
  gill filaments
• Gill Filaments fingerlike projections where
  oxygen is absorbed and carbon dioxide is removed

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Parts of a Gill
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• Fish Breathing

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How Fish Breathe
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Counter-Current System

• Gas is exchanged in gills because water and blood
  move along side each other in opposite directions

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PRESSURE AND DEPTH

• A column of water only 10 m deep exerts a
  pressure of 1 ATM. Every 10 m of water exerts
  another ATM of pressure. Organisms living at 100m
  or 500m are subjected to 10 ATM or 50 ATM (plus 1
  ATM of air pressure above the sea).

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PRESSURE AND DEPTH
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Fish and Body Temperature

• Types of temperature systems
• Endothermic (homeothermic) maintain a constant
  internal body temperature (ex. Humans 98.60F)
• Ectothermic or Poikilothermic - have a
  temperature similar to their surroundings (ex. If
  the water is 560F F then the fish will have a
  body temperature around 560F)

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Fish Reproduction

• Most fish have internal sex organs that we cannot
  see.
• fish gonads (sex organs) produce gametes (sex
  cells) only at certain times.
• These times must be the same for both males and
  females and must be timed to the most favorable
  conditions.

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Fish Reproduction

• Fish may only reproduce when there
• 1. Is enough of the right kind of food
• 2.There are enough hours of light each day
• 3. The water is the right temperature

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Fish Reproduction

• Includes
• Courtship a series of behaviors designed to
  attract mates
• Spawning a release of gametes into the water
• Copulation a direct transfer of sperm into a
  females body

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Fish Reproduction

• Most fish reproduce by spawning.
• This is when the female swims and lays eggs on
  plants or sand in the water
• The male fish swims behind her depositing sperm
  into the water where some of it may land on and
  fertilize the eggs

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Sunfish Spawning
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Fish Reproduction

• Other Fish give birth to live young like humans
  (ex. Guppy giving birth)

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Fish Reproduction

• Some fishes are hermaphrodites. They have both
  male and female gonads
• Hermaphrodism is more common among the deep-water
  fishes. (Gourami)

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Deep Sea Fish

• Deep Sea Fangtooth

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Fish Reproduction

• Reproduction in fishes involves many adaptations
  that help individuals get together and select
  mates.

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Fish Courtship

• Mandarin Fish Dancing to attract a female

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Fish Reproduction

• Sex Reversal
• Males may change to females or females to males
  (ex. Clownfish)

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Sex Reversal

• Among some species of anemone fishes a single
  large female who mates only with a single large
  dominant male inhabits each sea anemone. All
  others are small non-breeding males. If the
  female disappears her mate changes into a female
  and the largest of the non-breeding males becomes
  the new dominant male. The new female can start
  spawning as soon as 26 days after her sex change.