Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall
Biology Copyright Pearson Prentice Hall

31-1 Reptiles Photo Credit: ©Bruce Coleman, Ltd./Natural Selection Copyright Pearson Prentice Hall

What Is a Reptile? What are the characteristics of reptiles? Copyright Pearson Prentice Hall

What Is a Reptile? What Is a Reptile? A reptile is a vertebrate that has dry, scaly skin, lungs, and terrestrial eggs with several membranes. These characteristics enable reptiles to live their entire lives out of water. Copyright Pearson Prentice Hall

What Is a Reptile? Reptilian skin is dry and covered with thick, protective scales. This prevents the loss of body water in dry environments. The scaly layer of skin doesn’t grow, so it must be shed periodically as the reptile increases in size. Copyright Pearson Prentice Hall

Evolution of Reptiles Evolution of Reptiles Reptiles were the first vertebrates that were not dependent on water for reproduction. The first reptile fossil dates back to the Carboniferous Period. Copyright Pearson Prentice Hall

Evolution of Reptiles Dinosaurs During the late Triassic and Jurassic periods, a great adaptive radiation of reptiles took place. The Mesozoic Era is often called the Age of Reptiles. Copyright Pearson Prentice Hall

Evolution of Reptiles Triassic Reptiles In the Triassic Period, reptiles such as these lived in the forests. The herbivorous Plateosaurus (left), nibbling on leaves, was a dinosaur, as were the group of carnivorous Coelophysis (center). The large carnivorous Teratosaurus (right) was a reptile but not a dinosaur. Copyright Pearson Prentice Hall

Evolution of Reptiles Dinosaur structure and behavior varied: Ranged in size from small to enormous. Ran on two legs or on four legs. Ate leafy plants or other animals. Some lived in small family groups. Some may have had feathers. Copyright Pearson Prentice Hall

Evolution of Reptiles All of dinosaurs belonged to one of two major groups: Ornithischia, or “bird-hipped” dinosaurs Saurischia, or “lizard-hipped” dinosaurs Copyright Pearson Prentice Hall

Evolution of Reptiles At the end of the Cretaceous, a mass extinction occurred that killed the dinosaurs as well as other plant and animal groups. Copyright Pearson Prentice Hall

Form and Function in Reptiles
How are reptiles adapted to life on land? Copyright Pearson Prentice Hall

Tough, scaly skin and the ability to control body temperature are two adaptations to terrestrial life. Copyright Pearson Prentice Hall

Adaptations that have contributed to the success of reptiles on land are: well-developed lungs a double-loop circulatory system a water-conserving excretory system strong limbs internal fertilization shelled, terrestrial eggs Copyright Pearson Prentice Hall

Body Temperature Control Reptiles are ectotherms. Ectotherms are animals that rely on behavior to control body temperature. To warm up, they bask in the sun or stay under water at night. To cool down, they move to the shade or take shelter in underground burrows. Copyright Pearson Prentice Hall

Feeding Reptiles eat a wide range of foods. Iguanas eat plants. Snakes eat small animals, bird eggs, or other snakes. Crocodiles and alligators eat fish and land animals. Chameleons eat insects. Copyright Pearson Prentice Hall

Respiration Reptile lungs are spongy, allowing for a larger area of gas-exchange. Many reptiles have muscles around the ribs that expand and collapse the chest cavity. Most reptiles have two lungs, but certain species of snakes have just one lung. Copyright Pearson Prentice Hall

Circulation Reptiles have a double-loop circulatory system: One loop brings blood to and from the lungs. One loop brings blood to and from the rest of the body. Copyright Pearson Prentice Hall

Liver Heart Kidney Cloaca The internal organs of most reptiles include a three-chambered heart with two atria and one partially divided ventricle. Digestive tract Lung Bladder Copyright Pearson Prentice Hall

Reptile hearts have two atria and either one or two ventricles. Most reptiles have one ventricle with a partial septum that separates oxygen-rich and oxygen-poor blood. Crocodiles and alligators have two atria and two ventricles. Copyright Pearson Prentice Hall

To body Right atrium From lungs To lungs Left atrium From body The internal organs of most reptiles include a three-chambered heart with two atria and one partially divided ventricle. Incomplete division Ventricle Copyright Pearson Prentice Hall

Excretion Urine is produced in the kidneys. In some reptiles, urine flows in tubes directly into a cloaca. In others, a bladder stores urine before it is expelled. Copyright Pearson Prentice Hall

Other reptiles convert ammonia into uric acid. In the cloaca, urine is reduced to crystals of uric acid that form a pasty white solid. By eliminating solid wastes, a reptile can conserve water. Copyright Pearson Prentice Hall

Response Reptilian brains are similar to amphibians. Their cerebrum and cerebellum are more developed than other parts of the brain. Copyright Pearson Prentice Hall

Reptiles that are active in the day have complex eyes and see color well. Many snakes also have an extremely good sense of smell. Most reptiles have sensory organs in the mouth that detect chemicals when reptiles flick their tongues. Copyright Pearson Prentice Hall

Reptiles have simple ears with an external eardrum and a single bone that conducts sound to the inner ear. Snakes can also pick up vibrations in the ground through bones in their skulls. Some snakes can detect the body heat of their prey. Copyright Pearson Prentice Hall

Movement Reptiles with legs have large strong limbs. Some have legs that are rotated further under the body, enabling them to carry more body weight. Copyright Pearson Prentice Hall

The legs and feet of many aquatic turtles have developed into flippers. Reptiles’ backbones help accomplish much of their movement. Copyright Pearson Prentice Hall

Reproduction Most reptiles are oviparous, laying eggs that develop outside the mother’s body. All reptiles reproduce by internal fertilization, in which the male deposits sperm inside the female’s cloaca. After fertilization, the female’s reproductive system covers the embryo with several membranes and a leathery shell. Copyright Pearson Prentice Hall

The shell and membranes protect the embryo and prevent the egg from drying out. This type of egg, an amniotic egg, is one of the most important adaptations to life on land. An amniotic egg has four membranes—the amnion, the yolk sac, the chorion, and the allantois. Copyright Pearson Prentice Hall

The amnion is a fluid-filled sac that surrounds and cushions the developing embryo. Amnion An amniotic egg contains several membranes and an external shell. Although it is waterproof, the egg shell is porous, allowing gases to pass through. The shell of reptile eggs is usually soft and leathery. The amniotic egg is one of the most important adaptations to life on dry land. Copyright Pearson Prentice Hall

The chorion regulates the transport of oxygen and carbon dioxide between the surface of the egg and the embryo. Chorion An amniotic egg contains several membranes and an external shell. Although it is waterproof, the egg shell is porous, allowing gases to pass through. The shell of reptile eggs is usually soft and leathery. The amniotic egg is one of the most important adaptations to life on dry land. Copyright Pearson Prentice Hall

The yolk sac contains the yolk that serves as a nutrient-rich food supply for the embryo. An amniotic egg contains several membranes and an external shell. Although it is waterproof, the egg shell is porous, allowing gases to pass through. The shell of reptile eggs is usually soft and leathery. The amniotic egg is one of the most important adaptations to life on dry land. Yolk sac Copyright Pearson Prentice Hall

The allantois stores the waste produced by the embryo. Allantois An amniotic egg contains several membranes and an external shell. Although it is waterproof, the egg shell is porous, allowing gases to pass through. The shell of reptile eggs is usually soft and leathery. The amniotic egg is one of the most important adaptations to life on dry land. Copyright Pearson Prentice Hall

Groups of Reptiles What are the four living orders of reptiles? Copyright Pearson Prentice Hall

Groups of Reptiles Groups of Reptiles The four surviving groups of reptiles are: lizards and snakes crocodilians turtles and tortoises tuatara Copyright Pearson Prentice Hall

Groups of Reptiles Lizards Most lizards have four legs and clawed toes. Most lizards have external ears and movable eyelids. Some lizards have evolved into highly specialized forms. Copyright Pearson Prentice Hall

Groups of Reptiles Snakes Snakes have no legs. Snakes have immovable eyelids and no external ear openings. Snakes are efficient predators. Copyright Pearson Prentice Hall

Groups of Reptiles Crocodilians Crocodilians have long, broad snouts and a squat appearance. They prey on animals such as fishes, deer, and even humans. Females guard their eggs from predators and watch over their young after the eggs hatch. Copyright Pearson Prentice Hall

Evolution of Reptiles Crocodilians live only where it is warm year-round. Alligators and caimans live only in fresh water and are found almost exclusively in North and South America. Crocodiles live in either fresh or salt water and are native to Africa, India, and Southeast Asia. Copyright Pearson Prentice Hall

Groups of Reptiles Turtles and Tortoises Turtles live in water. Tortoises live on land. A terrapin is a turtle that lives in water that is somewhat salty. Copyright Pearson Prentice Hall

Groups of Reptiles Turtles and tortoises have a two-part shell built into the skeleton: a dorsal part, or carapace a ventral part, or plastron The head, legs, and tail emerge from holes where the carapace and plastron join. Tortoises and most turtles pull into their shells for protection. Copyright Pearson Prentice Hall

Groups of Reptiles Tuataras Tuataras are found only on a few islands off New Zealand. They lack external ears and retain primitive scales. They have a “third eye,” which is part of a complex organ located on top of the brain. Copyright Pearson Prentice Hall

Ecology of Reptiles Ecology of Reptiles Many reptiles are in danger because of habitat destruction. Humans hunt reptiles for food, for pets, and for their skins. Laws protect some species, but more conservation efforts are needed to counteract their dwindling numbers. Copyright Pearson Prentice Hall

31-1 Copyright Pearson Prentice Hall

31-1 Most reptiles reproduce with external fertilization and external development. internal fertilization and internal development. internal fertilization and external development in water. internal fertilization and external development in shelled eggs. Copyright Pearson Prentice Hall

31-1 The yolk sac of a reptile egg functions as a membrane that exchanges oxygen and carbon dioxide for the embryo. membrane that stores wastes produced by the embryo. source of nutrient-rich food for the developing embryo. shock-absorbing fluid-filled sac protecting the embryo. Copyright Pearson Prentice Hall

31-1 Reptiles are a. ectotherms. b. endotherms. Copyright Pearson Prentice Hall

31-1 Reptiles with the most well-developed hearts include turtles and alligators. crocodiles and turtles. crocodiles and alligators. alligators and lizards. Copyright Pearson Prentice Hall

31-1 The two parts of a turtle or tortoise's shell are the terrapin and plastron. carapace and plastron. carapace and terrapin. terrapin and carapace. Copyright Pearson Prentice Hall

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