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The Sharks
Class Chondrichthyes
Class Chondrichthyes
• Includes sharks, skates and rays
Class Chondrichthyes
• Inhabited earth for 280 million
  years (twice as long as dinosaurs)
• 350 species of sharks
• 320 species of rays
• Found worldwide at all depths –
  almost all marine
Characteristics
• Cartilage instead of bone (chondros =
  cartilage)
• Lighter, more flexible
• Jaws and paired fins (unlike Class Agnatha)
Characteristics
• Streamlined body – torpedo shape - fusiform
• Placoid scales – denticles – small tooth-like
  plates – like sandpaper
• Counter-shading – dark on top, light on
  bottom – form of camouflage
External Anatomy
Internal Anatomy
Respiration
• 5 to 7 gill slits
• No operculum covering gill slits
• Water passes over gills, oxygen diffuses into
  blood, carbon dioxide out
• Some pump water through mouths, some,
  take in water through spiracle, others keep
  swimming
Buoyancy                liver

•   No swim bladder
•   Store oil in large liver
•   Heterocercal tail – asymmetrical – creates lift
•   Horizontal pectoral fins also provide lift
•   Cannot swim in reverse like bony fish
Senses
• Excellent sense of smell – nostrils only for
  smell, not breathing
• Simple, internal ear to hear low-frequency
  vibrations
Senses
• Electroperception – ability to detect weak
  electric currents
  – Ampullae of Lorenzini – in skin pores – find prey
    and for migration
• Lateral line – stretches from head to tail –
  fluid- filled sensory canals - sensitive to
  vibrations
Reproductio
                    n
                          claspers
• Separate sexes
• Usually internal fertilization – rare in fish
• Claspers – male structures to transfer sperm to
  female
• Some sharks give birth to live young
• Some sharks lay few, large eggs - mermaid’s
  purse
  – Durable case
  – Large yolk - nutrition
  – Well-developed young hatch
Feeding
• Ventral mouth
• Teeth – specialized denticles
• 6 – 20 rows deep
• Easily lost and replaced – up to 50,000 in a
  lifetime
• Hinged jaws – upper and lower can
work independently and in opposition
to each other
Feeding
• Many are predators
  – Eat fish, marine mammals
  – Speed
Feeding
• Some eat plankton
  – Whale shark – largest fish – up to 60 feet long
  – Filter plankton with open mouth
  – Low on food web
• Some are scavengers
Shark Attacks
•   Rare
•   Average of 6 per year worldwide
•   Very few species attack humans
•   Usually mistake humans for seals
Shark Attacks
• Great whites most dangerous – up to 23 feet
   and 3,000 pounds
• Other dangerous species: mako,
tiger, hammerhead
Symbiosis
• Remora - suckerfish
• Mutualistic symbiotic relationship with shark
  – Picks up scraps and feeds on external parasites
Human Uses
• Food
  – Steaks
  – Shark fin soup
• Vitamin A in livers
• Skin – leather = shagreen
• Overfished
Rays and Skates
•   Flattened bodies
•   Broad, wing-like pectoral fins
•   Glide or “fly” through water
•   Both eyes on top of head
Rays and Skates
• Ventral mouth with “teeth” for
 scavenging and crushing invertebrates
• Largest feed on plankton
• Usually associated with ocean bottom
• Most not harmful
Sharks powerpoint

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Sharks powerpoint

  • 2. Class Chondrichthyes • Includes sharks, skates and rays
  • 3. Class Chondrichthyes • Inhabited earth for 280 million years (twice as long as dinosaurs) • 350 species of sharks • 320 species of rays • Found worldwide at all depths – almost all marine
  • 4. Characteristics • Cartilage instead of bone (chondros = cartilage) • Lighter, more flexible • Jaws and paired fins (unlike Class Agnatha)
  • 5. Characteristics • Streamlined body – torpedo shape - fusiform • Placoid scales – denticles – small tooth-like plates – like sandpaper • Counter-shading – dark on top, light on bottom – form of camouflage
  • 8. Respiration • 5 to 7 gill slits • No operculum covering gill slits • Water passes over gills, oxygen diffuses into blood, carbon dioxide out • Some pump water through mouths, some, take in water through spiracle, others keep swimming
  • 9. Buoyancy liver • No swim bladder • Store oil in large liver • Heterocercal tail – asymmetrical – creates lift • Horizontal pectoral fins also provide lift • Cannot swim in reverse like bony fish
  • 10. Senses • Excellent sense of smell – nostrils only for smell, not breathing • Simple, internal ear to hear low-frequency vibrations
  • 11. Senses • Electroperception – ability to detect weak electric currents – Ampullae of Lorenzini – in skin pores – find prey and for migration • Lateral line – stretches from head to tail – fluid- filled sensory canals - sensitive to vibrations
  • 12. Reproductio n claspers • Separate sexes • Usually internal fertilization – rare in fish • Claspers – male structures to transfer sperm to female • Some sharks give birth to live young • Some sharks lay few, large eggs - mermaid’s purse – Durable case – Large yolk - nutrition – Well-developed young hatch
  • 13. Feeding • Ventral mouth • Teeth – specialized denticles • 6 – 20 rows deep • Easily lost and replaced – up to 50,000 in a lifetime • Hinged jaws – upper and lower can work independently and in opposition to each other
  • 14. Feeding • Many are predators – Eat fish, marine mammals – Speed
  • 15. Feeding • Some eat plankton – Whale shark – largest fish – up to 60 feet long – Filter plankton with open mouth – Low on food web • Some are scavengers
  • 16. Shark Attacks • Rare • Average of 6 per year worldwide • Very few species attack humans • Usually mistake humans for seals
  • 17. Shark Attacks • Great whites most dangerous – up to 23 feet and 3,000 pounds • Other dangerous species: mako, tiger, hammerhead
  • 18. Symbiosis • Remora - suckerfish • Mutualistic symbiotic relationship with shark – Picks up scraps and feeds on external parasites
  • 19. Human Uses • Food – Steaks – Shark fin soup • Vitamin A in livers • Skin – leather = shagreen • Overfished
  • 20. Rays and Skates • Flattened bodies • Broad, wing-like pectoral fins • Glide or “fly” through water • Both eyes on top of head
  • 21. Rays and Skates • Ventral mouth with “teeth” for scavenging and crushing invertebrates • Largest feed on plankton • Usually associated with ocean bottom • Most not harmful