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Sharks, Skates, Rays and Chimeras

Sharks, Skates, Rays and Chimeras. Class Chondrichthyes. Subclass Elasmobranchii Sharks Skates and Rays Subclass Holocephali Chimaeras (Ratfish) Traits Habitats. Adaptations. Buoyancy Respiration External covering Feeding Movement Sensory systems. Buoyancy. Huge oil-filled liver

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Sharks, Skates, Rays and Chimeras

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  1. Sharks, Skates, Rays and Chimeras Class Chondrichthyes

  2. Class Chondrichthyes • Subclass Elasmobranchii • Sharks • Skates and Rays • Subclass Holocephali • Chimaeras (Ratfish) • Traits • Habitats Class Chondrichthyes

  3. Adaptations • Buoyancy • Respiration • External covering • Feeding • Movement • Sensory systems Class Chondrichthyes

  4. Buoyancy • Huge oil-filled liver • A shark that has an air weight of 1,000 kg. weighs only 3.3kg in water • Lift created by a heterocercal tail Class Chondrichthyes

  5. Caudal Fin Types • Heterocercal • Homocercal Class Chondrichthyes

  6. Respiration • Chondrichthyes employ 3 different methods of respiration • “Two pump” method • Ram ventilation • Spiracles Class Chondrichthyes

  7. Class Chondrichthyes

  8. External Covering • All Chondrichthyes have placoid scales in one form or another • Placoid scale modifications • Spine of stingray, dorsal spine of dogfish, defensive spines in the skate, and teeth Class Chondrichthyes

  9. Ganoid: Sturgeon & Paddlefish Placoid:Sharks, Skates and Rays Ctenoid Cycloid: Tarpon and Ladyfish Scale Types Class Chondrichthyes

  10. Feeding • Digestion • Spiral valve Class Chondrichthyes

  11. Movement • Pelagic sharks have rete mirabile Class Chondrichthyes

  12. Sensory Systems • Elasmobranchs a have well-developed sensory system which acts in concert to locate prey and find their way around the environment • Some species can detect a drop of blood as dilute as 1 part per billion • Also, very good at following an odor trail Class Chondrichthyes

  13. Sensory Systems • Hearing • Olfaction • Lateral line Class Chondrichthyes

  14. Sensory Systems • Visual systems are well developed for use during night and day • Tapetum lucidum = increased vision at night • Nictitating membrane Class Chondrichthyes

  15. Sensory Systems • Ampullae of Lorenzini Class Chondrichthyes

  16. Chondrichthyes Reproduction • Most species have extended gestation periods in egg cases or in the body cavities of females • Young traits • Internal fertilization, through the use of claspers on the male Class Chondrichthyes

  17. Chondrichthyes Reproduction • Oviparity • Viviparity • Yolk-sac Viviparity • Uterine Viviparity • Cannibal Viviparity • Placental Viviparity Class Chondrichthyes

  18. Oviparity - Egg Laying • Oviparity Class Chondrichthyes

  19. Viviparity • Yolk-sac Viviparity (Ovoviviparity) • Eggs are produced and retained inside the mother • Shell disappears and young are retained until fully developed • Uterine Viviparity • Mother secretes nutrient rich fluid which is taken up through the skin of the embryo Class Chondrichthyes

  20. Cannibal Viviparity • Young in each oviduct consume unfertilized eggs or other siblings Class Chondrichthyes

  21. Placental Viviparity • Nutrients are supplied to the embryo directly from the mother via a umbilical cord Class Chondrichthyes

  22. Chondrichthyes Life History • Strategy of Elasmobranchs • Produce precocial young with high survival rates • Slow growing, long lived, and reach sexual maturity at a late age • This reproductive strategy is why elasmobranchs can not sustain an intensive fishery Class Chondrichthyes

  23. Class Chondrichthyes • Subclass Holocephali • Possess cartilaginous skeleton, intromittent organs, spiral valve intestine, and oil filled liver • As a group found mostly between 80-2,600 meters, feeding on hard shelled invertebrates Class Chondrichthyes

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