Today

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Todays Fishes

• Section 33.2

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Jawless Fish - Agnathans

• Lampreys and hagfish
• Scaleless
• Eel-like bodies
• Multiple gill slits
• Unpaired fins
• Skeletons of cartilage
• Hagfish vultures of the sea scavengers
• Lamprey parasites on other living fish

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Hagfish
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Lampreys
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Cartilaginous Fishes

• Sharks, skates and rays
• Skeletons made of cartilage strengthened with
  calcium carbonate lightweight and strong
• Streamlined body
• Placoid scales give skin a rough texture
• Teeth are modified scales and are replaced as
  needed throughout lifetime

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Shark
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Skateroundish or triangular shape
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Raykite-shaped with 1 or more venomous barbs in
the tail
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Bony Fishes

• Largest group of fish
• Endoskeleton made of bone
• Lateral line system acts as a sensory organ to
  detect movement in the water (theirs and other
  objects)
• Operculum hard gill cover which allows fish to
  move water over the gill while remaining still in
  the water
• helps fish conserve energy
• Swim bladder allows fish to maintain water
  depth
• gas in ? fish rises gas out? fish sinks
• Two groups ray-finned fish lobe-finned fish

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Ray-finned fish

• Most fish are in this group
• Teleosts the most advanced
• Highly mobile fins
• Very thin scales
• Completely symmetrical tails
• 95 of all fish species

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Yellow perch a ray-finned fish
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Lobe-finned fish

• Only 7 species 1 coelacanth 6 lung fish
• Each fin has a long, fleshy, muscular lobe
  supported by a central core of bones
• May be a direct ancestor of amphibians, but
  probably not

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Coelacanth
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Lung fish