Sharks

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Sharks

  1. 1. Sharks Read pages 155-159 & 174-177 See also: http://www.flmnh.ufl.edu/fish/education/questions/basics.html
  2. 2. Types of Fishes – Where Do Sharks Fit In? <ul><li>Three types: Jawless, Cartilaginous, & Bony </li></ul><ul><li>Sharks fall into the Cartilaginous category </li></ul><ul><ul><li>Primitive fishes </li></ul></ul><ul><ul><li>No true bones, only cartilage </li></ul></ul><ul><ul><li>Related to skates and rays </li></ul></ul><ul><ul><li>Most are harmless </li></ul></ul><ul><ul><li>See the model in C114 </li></ul></ul>
  3. 3. Shark Diversity <ul><li>The smallest shark is a deepwater dogfish (adults are about 8 inches long)  </li></ul><ul><li>The largest shark is the whale shark </li></ul><ul><li>(a planktivore)  </li></ul><ul><li>The fastest shark is the shortfin mako (swims up to 20 mph) </li></ul><ul><li>(Note: Average person swims about 3 mph) </li></ul>http://dsc.discovery.com/videos/ultimate-guide-to-sharks-the-many-species-of-sharks.html
  4. 4. Shark Bodies <ul><li>Notice that sharks are fish and obtain oxygen from the water through their gills-usually 5 – 7 gills </li></ul>
  5. 5. Shark Bodies Cont. <ul><li>Lost teeth are replaced in a “conveyor belt” system, with back teeth moving forward to replace lost ones </li></ul>
  6. 6. Shark Bodies Cont. <ul><li>Placoid Scales – sharp-edged scales can injure prey; gives shark skin a sandpaper-like feel </li></ul><ul><li>Liver – very fatty; helps shark maintain buoyancy </li></ul><ul><li>Tail-upper lobe is usually longer for better power & thrust </li></ul><ul><li>Usually two dorsal fins, paired pectoral fins </li></ul>
  7. 7. Shark Reproduction <ul><li>Fertilization is internal </li></ul><ul><li>Males use claspers to insert sperm into female’s cloaca </li></ul>
  8. 8. Shark Reproduction Cont. <ul><li>Some sharks are Oviparous (lay an egg-mermaids’ purse) </li></ul><ul><li>Some sharks are Ovoviviparous (have an egg that develops inside female-sometimes eating siblings!) </li></ul><ul><li>Rarely, sharks can be Viviparous (Live-bearers-like mammals) </li></ul>http://dsc.discovery.com/videos/ultimate-guide-to-sharks-how-are-sharks-born-take-a-look.html
  9. 9. Shark Camouflage <ul><li>Countershading – darker on dorsal surface to blend with the deeper water or the sea bottom & lighter on ventral surface to blend with lighter colored surface waters, making it difficult for both predators & prey to see a shark </li></ul>
  10. 10. Shark Trouble <ul><li>Most sharks need to force water over gills to breathe, and can “drown” when trapped in nets </li></ul><ul><li>Skin, oil, and fins are overharvested to the point of near extinction for some species </li></ul><ul><li>PSA aimed at stopping these practices: http:// www.youtube.com/watch?v =fkxoRPv4ugE&playnext=1&list=PLB4E6B7A755C66293 </li></ul>
  11. 11. Additional Shark Links <ul><li>More on the importance of sharks in healthy oceans: http://www.youtube.com/watch?v=xVKrwsXvC0A&feature=autoplay&list=PLB4E6B7A755C66293&index=5&playnext=2 </li></ul><ul><li>Clearinghouse of all known Shark links: http://www.postmodern.com/~fi/sharklinks/links.htm </li></ul><ul><li>More general shark information: http:// www.youtube.com/watch?v =xVKrwsXvC0A&feature= autoplay&list =PLB4E6B7A755C66293&index=5&playnext=2 </li></ul>

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