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Chapter 34

Chapter 34. Reptiles and Birds. Section 1. The Reptilian Body. Key Characteristics of Reptiles. Relatives of dinosaurs Important members of ecosystems Kill insect pests and small rodents Some are poisonous/dangerous Many go unnoticed. Can’t live in cold climates

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Chapter 34

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  1. Chapter 34 Reptiles and Birds

  2. Section 1 The Reptilian Body

  3. Key Characteristics of Reptiles • Relatives of dinosaurs • Important members of ecosystems • Kill insect pests and small rodents • Some are poisonous/dangerous • Many go unnoticed • Can’t live in cold climates • Not conducive to ectothermic organisms • Bony skeleton and 2 pairs of limbs • Excepts snakes and some lizards • Toes with claws • Small brains in relation to their body

  4. Ectothermic Metabolism • Must absorb heat from their surroundings • Metabolism is too slow to generate enough heat to warm their bodies • Use the sun to warm their bodies and shade to cool their bodies • Become very sluggish during cold periods • Temperature is major limiting factor on their range

  5. Water Retention • Amphibians must spend time in water to compensate for extra water loss, reproduce and develop • Not fully terrestrial • Reptiles have evolutionary adaptations to avoid this • Watertight skin • Watertight eggs

  6. Watertight Skin • Terrestrial animals are susceptible to water loss through their skin • Reptiles have skin of light, flexible scales • Scales overlap to form a nearly watertight skin • Decreases amount of water lost through skin

  7. Watertight Eggs • Sperm and eggs dry out without watery environment • Fertilized eggs require a moist environment • Amniotic egg • Contain a water and food supply • Shell is essentially watertight • Does not dry out • Most reptiles, birds and some mammals utilize the amniotic egg • Amniotic egg suggests that birds, reptiles and mammals evolved from a common ancestor

  8. Respiration • Usually more active than amphibians • Require greater metabolic processes to obtain oxygen • Utilize lungs and heart

  9. Lungs • Scaly skin does not allow gas exchange • Can’t use skin as additional respiratory surface like amphibians • Lungs of reptiles have internal folds that increase the surface area/capacity • Reptiles have large muscles that attach to their rib cage • Muscle help move air in and out, increasing efficiency

  10. Heart • Oxygen-rich and poor blood mix in an amphibians ventricle • Reptiles have a septum that allows for the separation of blood • Oxygen is delivered to the body more efficiently • Crocodiles have a completely divided heart • Allows for even greater efficiency • p. 776 – fig. 5

  11. Reproduction • Eggs fertilized within females • Oviparous • Young hatch from eggs • Susceptible to predators • Ovoviviparous • Female retains the eggs within their body until right before hatching or until egg hatches • Less susceptible to predators

  12. Section 2 Today’s Reptiles

  13. Lizard • Order Squamata • Include iguanas, chameleons, geckos, horned lizards • Most are carnivores • 1 – 10 ft. long • Can regenerate tail

  14. Snakes • Order: Squamata • Lack moveable eyelids and external ears • Molt periodically • Flexible jaw • 5 points of movement • Constrictors • Squeeze prey until they suffocate • No teeth for cutting or chewing • Swallow prey whole • Some contain venomous fangs

  15. Turtles and Tortoises • Order: Chelonia • Body encased in hard protective shell • Consists of 2 parts • Carapace – dorsal side of shell • Plastron – ventral side of shell • Able to pull limbs inside shell for protection • Shell shaped due to habitat • Lack teeth, but jaws are covered by sharp plates • Most are herbivores • Snapping turtle is carnivorous

  16. Crocodiles • Order: Crocodilia • Most closely related to dinosaurs • Aggressive carnivores • Reach as long as 20 ft. in some areas • Very stealthy • Often sneak up on prey • Eyes and snout on top of head • Can see and breath while body is submerged • Care for young after hatching

  17. Tuataras • Order: Rynchocephalia • Native to New Zealand • Lizard-like reptiles • Reach up to 2 ft. • Most active during cooler temperatures • Nearly unchanged for the last 150 million years • Numbers are currently declining

  18. Section 3 Characteristics and Diversity of Birds

  19. Key Characteristics of Birds • Members of class Aves • Some species can’t fly • Usually lack teeth • Lay amniotic eggs • Feet and legs covered with scales • Presence of feathers and modification of forelimb into wings • Body covered with feathers • Lightweight bones • Endothermic metabolism • Very efficient respiratory system • Completely divided ventricle

  20. Feathers • Modified reptilian scales • Birds molt and replace their feathers • Usually doesn’t happen at once • 2 main types: • Contour • Cover birds body and give them their shape • Provide lift for flight • Down • Cover young birds and found under contour feathers • Preening • Linking of barbs of feathers • Preen gland • Secretes oil that cleans and waterproofs feathers

  21. Strong, Lightweight Skeleton • Bones are thin and hollow • Many bones are fused, making the skeleton very rigid • Large breast muscles • Provide power for flight and swimming • Fused collarbone and keeled breastbone

  22. Endothermic Metabolism • Warm-blooded • Metabolism generates enough heat to warm body • 104-108 F • High temp. due to high rate of metabolism required to produce energy for flight • Hummingbirds – range 20-80 wing beats per second

  23. Completely Divided Ventricle • Ventricle completely divided by septum • Keeps oxygen-rich and oxygen-poor blood separate • Oxygen is delivered to the body more efficiently • Hummingbirds may have ~1000 heart beats per minute

  24. Highly Efficient Lungs • Birds require large amounts of energy during flight • One-way oxygen flow • Made possible by air sacs connected to their lungs • Sacs are a holding tanks of air • p. 787 – figure 18 • 2 advantages of one-way air flow • Lungs exposed to air that is nearly entirely oxygenated • Blood and oxygen flowing in opposite directions increases absorption

  25. Adaptations of Birds • Made possible by differences in beaks, legs, and feet • Talons for grasping prey • Beaks for shoveling mud or moving water • Webbed feet for swimming • Beaks for crushing seeds • Curved feet for grasping branches • Wings modified for swimming • Adaptations allow birds to utilize various resources

  26. Other Adaptations • Seagulls body shape allows them to fly over water • Streamlined • Owls eyesight allows them to hunt at night • Nocturnal

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