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The Reptile Body

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  1. The Reptile Body

  2. Characteristics of Reptiles • Reptiles were the first vertebrates to live on land • Scales keep moisture inside • Reptiles eggs DO NOT dry out on land • Live in a variety of different habitats • Tropical forests, des\serts, oceans, rivers, and lakes • Are NOT found in very cold regions because they are cold-blooded

  3. Characteristics of Reptiles • All reptiles share the following characteristics • Bodies covered in scales • Clawed toes • Ectothermic (cold-blooded) metabolism • Lack feathers or any form of hair • An internal skeleton • A heart with a partially divided ventricle • Lungs • Reproduce Internally • Amniotic eggs

  4. Reptile Movement and Response • The following adaptations allow reptiles to live in dry environments • A strong skeleton • Claws • legs positioned under the body • highly developed vision • Since Reptiles are cold-blooded this limits their habitat range

  5. Endoskeleton • Reptiles have a strong skeleton made of bone • Mostreptiles have two pairs of limbs • Snakes and some lizards lack legs • Legs positioned under the body allow reptiles to move faster and easier on land • Reptiles have toes with claws • Use claws for climbing and digging • Enables reptiles to run quickly over short distances

  6. Sensory Systems: Vision • Vision is an important sense • Rely on sight to detect predators and prey • Eyes of reptiles are very large and have movable eyelids • Snakes and geckos lack movable eyelids • Reptiles that are active at night can see very well in the dark

  7. Sensory Systems: Hearing • Hearing is a very important sense organ to reptiles • Sound waves first strikes the tympanum (ear drum) and are then transmitted to the inner ear • Snakes lack a tympanum • They detect ground vibrations through the bones of their jaw

  8. Sensory Systems: Jacobson’s Organ • Reptiles sticks their tongues out to collect small particles from the air • The small particles come in contact with the Jacobson’s Organ • The Jacobson’s Organ is a specialized sense organ in the roof of the mouth of many reptiles, it is sensitive to odors • Used to “taste” the environment

  9. Sensory System • Snakes are able to detect heat given off by warm-bloodied prey • Use heat sensitive pits below each eye • The pits allow the snake to detect the distance and direction of the prey

  10. Body Temperature Control • Reptiles are ectothermic • They CANNOT heat their own body by using their metabolism • A reptile’s body temperature is mostly determined by the temperature of its environment • Reptiles may bask in the sun to warm up or seek shade to cool down • At very low temperatures reptiles slow down and may not be able to function

  11. Respiration and Circulation • The following adaptations allow reptiles to have more efficient respiration and circulation • 1. Lungs with a large surface area • 2. A heart that is almost completely divided into four chambers

  12. Reptile Lungs • Reptile lungs have many internal folds, which gives the lungs a large surface area for oxygen exchange • Strong muscles in the rib cage allow air to move in and out of the lungs quickly, which increases lung efficiency

  13. Reptile Heart • The septum partly divides the ventricle into right and left halves • Enables a much better, but still incomplete, separation of oxygen-rich and oxygen-poor blood • Oxygen is delivered to the body cells more efficiently in reptiles than in amphibians

  14. Reptile Reproduction • Reptile reproduction occurs through internal fertilization • Many reptiles are oviparous: the young hatch from eggs that are laid outside the mother’s body. • Some snakes are lizards are ovoviviparous: fertilized eggs remain inside the female’s body for a long time and hatch inside the female • This protects the eggs from predators • Most reptiles DO NOT care for their young • Alligators and crocodiles are an exception

  15. Amniotic Eggs • An amniotic egg contains both a water supply and food supply • Amniotic eggs are key to a reptile’s success as a terrestrial animal • They are watertight

  16. Amniotic Egg Structure • The shell and albumen protects and cushions the embryo • Also a source of nutrients • There are four membranes in the amniotic egg • 1. Amnion- cushions the embryo • 2. Yolk Sac- contains the embryo’s main food supply, blood vessels attach here • 3. Allantois- stores waste and is the embryo’s organ for gas exchange • 4. Chorion- allows oxygen to enter the egg and carbon dioxide to leave the egg

  17. Review Questions • 1. Identify seven characteristics of reptiles • 2. Describe how being ectothermic influences a reptile’s lifestyle • 3. Explain how reptiles meet their need for oxygen • 4. Summarize how the amniotic egg allows reptiles to live on land • 5. Do you think a reptile that cares for its young lays more or fewer eggs than a reptile that doesn’t care for its young? Explain