Reptiles EQ: What are reptiles?

What is a reptile? A vertebrate that has dry, scaly skin, lungs, and terrestrial eggs, with several membranes While reptiles have a dry waterproof skin, it doesn’t grow with the reptile, therefore they must shed periodically Reptiles live everywhere except in very cold areas

Evolution of Reptiles Reptiles evolved from amphibian-like ancestors Early reptile fossils date back to the Carboniferous period (350 million years ago) End of the Permian Period (245 million years ago) there was a great variety of reptiles due to the drier climate (negative impact on amphibians) During this time, mammalian reptiles started to appear (link between reptiles & mammals) Mesozoic Era (late Triassic & Jurassic periods) = Age of Reptiles

Dinosaurs Triassic Period (215 million years ago)- dinosaurs became dominant Great variety of species, eating habits, and behaviors End of the Cretaceous Period (about 65 million years ago)- mass extinction occurred worldwide The extinction of dinosaurs gave way for other organisms to evolve

Body Temperature Controls Ectotherms- behavior to control body temperature Bask in the sun for heat

Feeding Wide range Herbivores (Iguana, turtles)- tear plants to shreds and long digestive tract enables the breakdown of the plant material Carnivores (snakes, chameleons, crocodiles, alligators, etc)- prey on small animals, bird eggs, fish, insects

Respiration Lungs (more spongy than amphibians) with muscles surrounding to help expand/collapse the chest cavity Most have 2 lungs (some snakes have 1)

Circulation Double-loop system (like amphibians) Most have 3-chambered heart Crocodiles and alligators have 4-chambered hearts (also found in birds and mammals)

Excretion Reptiles that live primarily in water excrete waste as ammonia since they are able to drink large amounts of water Reptiles that live primarily on land instead convert the ammonia into uric acid and will form a white pasty solid to conserve water

Response Reptile’s brain is similar to amphibian’s Diurnal reptiles tend to have complex eyes and can see color Many snakes have good sense of smell Most reptiles have a sensory organ in the roof of their mouth that can detect chemicals when they flick their tongues Snakes can detect body heat and vibrations

Movement Reptiles with legs have larger and stronger limbs than amphibians Many aquatic turtles developed their legs into flippers

Reproduction All reptiles internal fertilization (male deposits sperm into female) Most are oviparous (lays eggs) Some (ex. Box turtles) will make a nest and abandon the eggs while others (ex. Alligators) will defend their nests/eggs Amniotic egg- an egg that developed a shell to protect the egg without needing to be in water One of the most important adaptions to living on land Others are Ovoviviparous (live birth) Ex. Some snakes and lizards

Groups of Reptiles: Lizards & Snakes Order: Squamata (scaly reptiles) Some lizards developed highly specialized forms, such as the Gila monsters who have glands in the lower jaw that produces venom Snakes are legless, but they are highly efficient predators Some are as small as earthworms, while others can grow more than 8 meters (24 feet)

Groups of Reptiles: Crocodillians Order- Crocodilia Includes: Crocodiles, caimans, alligators, and gavials Fierce carnivores that prey on deer, fish, and even humans Very protective of their young Lives in tropics and subtropics where it is warm year-round Alligators and caimans live only in fresh water are exclusively in North and South America Crocodiles can live in fresh and salt waters and are native to Africa, India, and Southeast Asia

Groups of Reptiles: Turtles and Tortoises Order- Testudines Turtles refer to members that live in water while tortoises refer to members that live on land Both have shells on the back, though not all are hard; the shell consists of 2 parts the carapace (top part) and the plastron (bottom part) They lack teeth, have horny ridges that covers powerful jaws

Groups of Reptiles: Tuatara Order- Sphenodonta Found only on a few small islands off the coast of New Zealand Resembles lizards but lack external ears and retain primitive scales Has a ‘third eye’ that can detect levels of sunlight