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Reptiles and Birds

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  1. Reptiles and Birds Unit 5 Chapter 26-2

  2. Reddish-Brown Frilled Lizard http://gladstone.uoregon.edu/~mkrueger/reptiles/types.htm

  3. Reptiles • Major characteristics: 1. Terrestrial 2. Do not need to reproduce in water 3. Have an amniotic egg to provide embryo with moist environment 4. Watertight skin (made of keratin) 5. Use lungs to respire 6. Excrete uric acid (solid)

  4. Reptile Evolution • Reptiles evolved from amphibians • Earliest fossils found are from the Carboniferous period (360-286 mya) • Fed on insects • Mesozoic era (245 -65 mya)= Age of Reptiles • Large reptiles were dominant (dinosaurs)

  5. Extinction of Dinosaurs • Asteriod-Impact hypothesis: asteroid hit Earth, caused huge clouds of dust, blocking sunlight (evidence=soil containing iridium) http://www.nmnh.si.edu/paleo/blast/

  6. Four Modern Orders of Reptiles • Turtles and tortoises • Lizards and snakes • Tuataras • Crocodillians *More than 6,000 species of reptiles exist today Tuatara http://www.volny.cz/martin.sliva/NovyZeland/Flora-Fauna/haterie_novozelandska.htm

  7. Reproduction in Reptiles • Oviparity is most common among species • Egg encased in a secure, self-contained aquatic environment • Amniotic eggs provide protection, nutrients, waste storage

  8. Amniotic Egg http://uk.encarta.msn.com/media_461517464_761562707_-1_1/Amniotic_Egg.html

  9. Circulatory System • 3 chambers: 2 atria and 1 partially separated ventricle (almost 4 chambers) • Two loops: pulmonary loop and systemic loop • Pulmonary loop carries blood to and from lungs • Systemic loop carries blood to and from body tissues

  10. Respiratory System • Large lungs • Alveoli (air sacs within the lungs where gas exchange occurs) • Reptiles, when inactive, can go for a long time without breathing.

  11. Nervous System • Vision is an important sense for reptiles • Hearing is also important • Jacobson’s organ- specialized sense organ located in the roof of the mouth of reptiles, sensitive to odors -tongue transfers chemicals to Jacobson’s organ for it to interpret

  12. Thermoregulation • Thermoregulation- control of body temp. • Ectotherms- warms its body by absorbing heat from its surroundings (fish, amphibians, reptiles) • Endotherms- have a rapid metabolism that generates heat needed to warm the body (mammals and birds)

  13. Birds

  14. Birds (Class: Aves) • Major Characteristics: 1. Feathers (insulation, flight) 2. Wings (modified forelimbs) 3. Lightweight rigid skeleton 4. Endothermic metabolism 5. Beak 6. Oviparity

  15. Evolution • Birds are believed to have evolved from small, fast-running carnivorous dinosaurs • Birds had to evolve anatomical, physiological and behavioral adaptations for life in the air 1. Wings 2. Hollow bones 3. Feathers

  16. Feathers • Feathers are modified scales: facilitate flight, conserve body heat. • Barbules on feathers interlock • Preening- birds use their beaks to rub their feathers with oil secreted by the preening gland. • Birds molt their feathers

  17. Structure of a Feather http://numbat.murdoch.edu.au/Anatomy/avian/fig2.6.GIF

  18. Thermoregulation • Birds are endothermic • Have a high metabolism: rapid breathing and digestion • Aquatic birds have a thin layer of fat that provides additional insulation

  19. Digestive System • Birds do not have teeth • Food passes directly through the esophagus to the two-part stomach • 1. 1st chamber= proventriculus (acid, enzymes break down food) • 2. 2nd chamber= gizzard (kneads and crushes food) • Small intestine- further broken down and absorbed

  20. Excretion • Kidneys excrete uric acid (solid nitrogenous waste) helps to conserve waste

  21. Circulatory System • 4 chambers • Deoxygenated and oxygenated blood is kept separate. • Birds have rapid heart rates Example: hummingbird’s heart beats 600 times per minute

  22. Bird’s Heart

  23. Nervous system • Highly developed cerebellum to control balance, and flight • Highly developed sense of vision: can discriminate color, depth • Hearing is important to songbirds and nocturnal species

  24. Reproduction • Lay eggs • One or both parents incubate, or warm the eggs • Young, once hatched, receive extensive parental care

  25. Bird’s Nest http://www.greenscreen.org/newsletter/articlesjr/images/birdsnest.gif