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