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Reptiles Copyright McGraw-Hill Education Characteristics of Reptiles Reptiles are fully adapted to life on land. Characteristics that allow reptiles to succeed on land include a shelled egg, scaly skin, and more efficient circulatory and respiratory systems.

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Reptiles Copyright McGraw-Hill Education Characteristics of Reptiles Amniotic eggs The amnion is a membrane that surrounds a developing embryo. An amniotic egg is covered with a protective shell and has several internal membranes. The leathery shell protects the internal fluids and embryo.

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Reptiles Copyright McGraw-Hill Education Characteristics of Reptiles Dry, scaly skin Dry skin keeps reptiles from losing internal fluids to the air. A layer of external scales keeps reptiles from drying out. Some reptiles, like snakes, must shed their skins to grow.

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Reptiles Copyright McGraw-Hill Education Characteristics of Reptiles Respiration Reptiles depend primarily on lungs for gas exchange. A reptiles lungs have a large surface area. With more oxygen, more energy can be released through metabolic reactions and made available for more complex movements.

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Reptiles Copyright McGraw-Hill Education Characteristics of Reptiles Circulation Similar circulatory system to amphibians Most reptiles have two separate atria and one partially divided ventricle.

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Reptiles Copyright McGraw-Hill Education Characteristics of Reptiles Feeding and digestion Similar digestive system to amphibians and fish Diversity of diets and feeding methods

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Reptiles Copyright McGraw-Hill Education Characteristics of Reptiles Excretion Kidneys filter the blood to remove waste products. Water reabsorption enables reptiles to conserve water and maintain homeostasis in their bodies.

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Reptiles Copyright McGraw-Hill Education Characteristics of Reptiles The brain and senses Vision is the main sense in most reptiles. Some reptiles have tympanic membranes and others detect vibrations through their jaw bones. In snakes, Jacobsons organs in the mouth are used to sense odors.

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Reptiles Copyright McGraw-Hill Education Characteristics of Reptiles Temperature control Reptiles are ectotherms and regulate their body temperatures by basking in the sun for warmth or burrowing in the ground to cool off. Survive cold winters by burrowing or going into a state of inactivity Movement Some reptiles move with limbs sprawled to their sides and push against the ground, others have limbs rotated further under the body to more efficiently bear weight. Reptile skeletons are stronger, with heavier bones.

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Reptiles Copyright McGraw-Hill Education Characteristics of Reptiles Reproduction Reptiles have internal fertilization. After fertilization, the egg develops to form the new embryo and an amniotic egg. Most reptile eggs are buried and the sun incubates them. After laying their eggs, most females leave them alone to hatch.

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Reptiles Copyright McGraw-Hill Education Diversity of Modern Reptiles Lizards and snakes Lizards have legs with clawed toes, moveable eyelids, a lower jaw with a moveable hinge joint, and tympanic membranes. Snakes are legless, have shorter tails than lizards, lack movable eyelids and tympanic membranes.

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Reptiles Copyright McGraw-Hill Education Diversity of Modern Reptiles Turtles A protective shell encases a turtles body. The dorsal part of the shell is the carapace. The ventral part of the shell is the plastron. No teeth, instead turtles have a sharp beak.

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Reptiles Copyright McGraw-Hill Education Diversity of Modern Reptiles Crocodiles and alligators Crocodilians (Crocodiles, alligators, and caimans) have a four-chambered heart which delivers oxygen more efficiently. Crocodile teeth are similar to those of dinosaurs and the earliest birds.

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Reptiles Copyright McGraw-Hill Education Diversity of Modern Reptiles Tuataras Tuataras look like large lizards and are found on the islands off the coast of New Zealand. Tuataras have a third eye located on the top of their heads that can detect sunlight. Tuataras have two rows of teeth on the upper jaw.

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Reptiles Copyright McGraw-Hill Education Evolution of Reptiles

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Reptiles Copyright McGraw-Hill Education Evolution of Reptiles Dinosaurs For 165 million years, dinosaurs dominated Earth. Divided into two groups based on hip structure: Saurischians and Ornithischians One group of dinosaurs likely had feathers and evolved into todays birds.

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Reptiles Copyright McGraw-Hill Education Ecology of Reptiles Habitat loss Reptiles are important as both predators and prey in the food web. Habitat fragmentation and destruction reduces reptile populations. Introduction of exotic species Human introduction of nonnative animals and plants affects reptile populations. Exotic species can feed on the reptiles themselves, or outcompete them for shared resources.

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Reptiles Copyright McGraw-Hill Education Review Essential Questions What is the importance of the amniotic egg in the transition to life on land? What are the characteristics of reptiles? What are the differences between orders of reptiles? Vocabulary amnion amniotic egg Jacobsons organ plastron carapace