Fish[1] - Fish The insects of the vertebrate world Fish...

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Fish The insects of the vertebrate world!
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Fish • Largest group of vertebrates (25,000+ species) • Adapted for life in the water • Diversified in the Devonian “The Age of Fishes” 400 MYA • Gill breathers with some exceptions • Two major living groups: Cartilaginous fish and the Boney fish
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The Gnathostomes The remaining vertebrates are Gnathostomes • Have jaws, and paired fins. • Jaws make them more effective as predators (able to grasp prey) • Paired fins make them more maneuverable. • Most things we think of as fish (plus all the land vertebrates) are gnathostomes.
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The Gnathostomes • Jaws appear to have evolved from gill-arch supports. • Embryological evidence supports this • Shape and positioning of jaws in sharks makes it clear that jaws are really gill arches, but are simply bigger.
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Cartilaginous Fish: Chondrichthyes Sharks and Rays • Stream-lined body in sharks • Ventral mouth • Bony scales • Teeth from modified scales • Cartilaginous endoskeleton • Separate and exposed gill slits • No swim bladder or lungs
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Sharks and rays have a variety of forms, from streamlined sharks to bottom-dwelling rays, with the pectoral fins fused to the head.
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Sharks must swim to maintain their place in the water column and breathe Pectoral fins Provide lift
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Jaws! • Shark jaws have sharp teeth to kill prey. • Once killed prey is often swallowed whole! • Teeth evolved from modified Boney scales
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Great White Sharks • Large (20 feet long), sometimes found in coastal areas like California • Prey on seals and sea lions • Sometimes confuse surfers with sea lions • 64 deaths since 1876
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Shark feeding on a Sea Lion
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Mistakes Happen!
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Why the Great White needs protection! Globally, white sharks are threatened by
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Fish[1] - Fish The insects of the vertebrate world Fish...

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