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Reptile Introduction. 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. Reptilian skin is dry and covered with thick, protective scales.
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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.
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.
Body Temperature Control • Reptiles are ectotherms. • Ectothermsare 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.
Reproduction • Most reptiles are oviparous, laying eggs that develop outside the mother’s body. • All reptiles reproduce by internal fertilization • This results in the formation of an egg
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.
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.
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.
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.
At the end of the Cretaceous, a mass extinction occurred that killed the dinosaurs as well as other plant and animal groups.
Yucatan Peninsula, Mexico The Chicxulub Crater is approximately 180 km (111 miles)in diameter and 10 km (6 miles)deep
Groups of Reptiles The four surviving groups of reptiles are: • lizards and snakes • crocodilians • turtles and tortoises • tuatara
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.
Lizards Blue Tongue Skink Bearded Dragon
Moniter Lizards Komodo Dragon
Snakes Snakes have no legs. Snakes have immovable eyelids and no external ear openings. Snakes are efficient predators.
Venomous Snakes: cobras, coral snake, sea snakes ……. types of venom: neurotoxin hemotoxin snake bite? antivenom shot
Largest Snake ever officially recorded: an Anaconda, captured & measured in 1944 South America - Orinoco River 37 1/2 feet! estimated to weigh nearly 600 pounds!
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.
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.
Crocodiles Crocs, Alligators, Caimens
Gharial (India) Alligator (USA) Crocodile (USA)
Turtles and Tortoises Turtles live in water. Tortoises live on land. A terrapin is a turtle that lives in water that is somewhat salty.
Turtles and tortoises have a two-part shell built into the skeleton: • a dorsal part (top), or carapace • a ventral part (bottom), 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.
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.