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Chapter 26

Chapter 26. Vertebrates A Summary. AP Biology Spring 2011. Chordates. Vertebrates include: Fish Amphibians Reptiles Birds Mammals Are coelomate, bilateral animals. Chordates. Many of 4 anatomical features that characterize chordates appear only during embryonic development

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Chapter 26

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  1. Chapter 26 Vertebrates A Summary AP Biology Spring 2011

  2. Chordates • Vertebrates include: • Fish • Amphibians • Reptiles • Birds • Mammals • Are coelomate, bilateral animals

  3. Chordates • Many of 4 anatomical features that characterize chordates appear only during embryonic development • Notochord: long, flexible rod that appears during embryonic development between the digestive tube and the dorsal nerve cord • Dorsal, hollow nerve cord: formed from a plate of ectoderm that rolls into a hollow tube • Pharyngeal clefts: grooves that separate a series of pouches along the sides of the pharynx; in most chordates the clefts develop into slits that allow water to enter and exit he mouth without going through the digestive tract • A muscular tail posterior to the anus

  4. Vertebrates • Have an internal skeleton and big brain • Internal skeleton: enlcoses and protects internal organs and works with muscles to produce movement • Have several advantages of external skeletons: • Cells are living so skeleton foes not have to be molted • Allows for greater flexibility • Is lightweight

  5. Vertebrates • Notochord develops into vertebral column which encloses and protects spinal cord • Have large brains with paired eyes and ears • With the exception of lampreys, have jaws

  6. Vertebrates • Circulatory and respiratory system • Paired gills evolved in early vertebrates and allowed for faster, more efficient gas exchange • Before transition to land, several species of fish developed small outpouchings in the side of the gut that evolved into lungs • Have a closed circulatory system which makes circulation faster • Gradually, there was less reliance on gills and more on lungs and circulatory system (heart, blood vessels), which work in connection

  7. Vertebrates • Other organ systems • Have paired kidneys to deal with internal fluid composition • Reproduce sexually • Have well developed immune system

  8. Gnathostomes • Vertebrates that have jaws • Jaws of vertebrates evolved from modification of skeletal parts that had once supported the pharyngeal (gill) slits

  9. Gnathostomes • Class Chondrichthyes: sharks and rays • Have flexible endoskeletons composed of cartilage, possess streamlined bodies, are denser than water, will sink if stop swimming

  10. Gnathostomes • Class Osteichthyes: bony fish • Most numerous of vertebrate groups • Two main classes of bony fish are ray finned and lobed fins • Have an ossified endoskeleton, covered in scales, posses a swim bladder

  11. Pisces • Fish • Are cold blooded vertebrates that have: • Gills • Scales • Two chambered heart

  12. Gnathostomes • Tetrapods that have four limbs and feet • Class amphibia • Not all have legs • Frogs

  13. Amphibia • Cold-blooded • Initially breath through gills • Then develop lungs • Can also exchange gas through their moist skin • Have a three chambered heart • Close ties with water • Their eggs lack a shell • Fertilization is external • Can exhibit complex social behaviour

  14. Amniotes • Tetrapods that have a terrestrially adapted egg • Consist of mammals and reptiles and birds • Amniotic egg • Important evolutionary development for life on land • Have shell that retains water and can be laid in a dry environment • Have extraembryonic membranes that function in gas exchange, waste storage and transport of nutrients to embryo

  15. Reptilia • Cold-blooded • Have eggs with a chitinous covering • Lay eggs on land • Undergo internal fertilization • Have a four chambered heart • First vertebrates to have internal fertilization • Have scales containing keratin • Adaptation for terrestrial living • Obtain oxygen through their lungs, not skin

  16. Reptilia • Extinct reptiles: • Dinosaurs (lived on land) • Pterosaurs (flying reptiles) • Plesiosaurs (marine reptiles) • Modern reptiles: • Turtles, tuataras, lizards, snakes, alligators, crocodiles • Most are ectothermic • Regulate body temperature through behavioral adaptations rather than by metabolism

  17. Aves • Birds • Warm-blooded • Have eggs with shells • Lay amniotic eggs • Wings, feathers, hollow bones • Four-chambered heart • High rate of metabolism • Have keratin containing scales on their legs • Scales and eggs are reptilian characteristics

  18. Aves • Most birds bodies are constructed for flight: • Light, hollow bones • Relatively few organs • Wings • Feathers • Endotherms: maintain warm, consistent body temperature • Feathers and in some cases a layer of fat insulate birds and help maintain internal temperature • Have larger brains than amphibians and nonbird reptiles do

  19. Mammalia • Warm-blooded (endotherms) • Active metabolism • Most are born rather than hatched • Use internal fertilization • Large brains • Four-chambered heart • Have hair and produce milk to feed their young • All have teeth of differing size and shape

  20. Mammalia • Some have a placenta (eutherians) • Structure that nourishes fetus • Embryo develops internally in a uterus connected to mother by placenta, where nutrients diffuse from mother to embryo

  21. Mammalia • Marsupials do not have a placenta • Developing embryo receives little nourishment from mother in the uterus • About eight days after fertilization, fetus must continue its maturation in mother’s pouch (nurses)

  22. Mammalia • Monotremes: egg laying mammals • Duck billed platypus and spiny anteater • Derive nutrients from shelled egg

  23. Mammalia: Primates • Humans are primates • Primates descended from insectivores, probably from small, tree dwelling mammals • Have dexterous hands and opposable thumbs • Make it possible to do fine motor tasks • Nails have replaced claws • Hands and fingers contain many nerve endings and are sensitive

  24. Mammalia: Primates • Eyes are front facing and set close together • Front facing eyes fosters face-to-face communication • Close set eyes are responsible for overlapping fields of vision, which enhances depth perception and hand-eye cordination

  25. Mammalia: Primates • Devote much energy to parenting of young • Engage in most intense parenting of any mammal • Usually have single births and nurture young for long time period

  26. Mammalia: Primates • Include: • Humans • Gorillas • Chimpanzees • Orangutans • Gibbons • Old world and new world monkeys

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