Transcript document
Ch. 41 - Reptiles Unlike amphibians, reptiles don’t have to return to the water to reproduce. They were the first vertebrates to live on land during their whole life cycle. Reptiles evolved a new reproductive structure that allowed them to reproduce on land. What is this structure? Amniote egg Amniote Egg ( 5 parts) 1. Porous shell – protects & prevents water loss. 2. Amnion – salty fluid that allows the embryo to float. 3. Allantois – excretes nitrogenous waste from the embryo 4. Chorion – lines the outer shell. Diffuses carbon dioxide & oxygen through the shell. 5. Yolk sac – supplies food for the embryo. Characteristics of Reptiles 1. Dry body covering (some with scales) Made of keratin to prevent water loss. 2. Lungs 3. 3-chambered heart with the ventricle partially divided. (alligators have 4) 4. Ectotherms – body temperature is influenced by the environment. 5. Limbs, if present, have toes with claws. 6. Internal Fertilization (big advantage) Origin of Reptiles Reptiles where thought to of arose from the cotylosaurs. Pg. 820 Mesozoic era is known as the Age of Reptiles. When were the dinosaurs thought to have become extinct? Cretaceous Period Dinosaur means “terrible lizard” Reptile Orders Cl.: Reptilia 1. Rhynochocephalia Tuatara – the only species in this order •Only in New Zealand •Parietal eye – “3rd eye” on the top of their head 2. Chelonia Turtles Dorsal shell is called the carapace Ventral shell is called the plastron A bridge connects the two. Turtles are protected very well with their shell. Snapping turtles are one of the more aggressive turtles. They have a worm-like tongue to attract fish. 3. Crocodilia Crocodiles & alligators Caimans (short & wide snout) & gavials (long & narrow snout). The only living relatives of the dinosaurs. Have you ever wondered why an alligator or crocodile doesn’t swallow a lot of water when it has its mouth open? It has a glottis that prevents this. Have you ever heard of the “Crocodile Man”? 4. Squamata Largest Order Lizards & Snakes There are only 2 poisonous lizards • 1. Gila Monster – S.W. U.S. Has grooved teeth with venom & shakes its head to release the venom. • 2. Beaded Lizard – Western Mexico Name as many lizards a possible • Iguanas, horned toads, chameleons, skinks, & geckos Horned lizards or horny toads live around here. They have armored spikes covering them and when disturbed they his and squirt blood out their eyelids. Skinks and geckos have the ability to lose their tails and regenerate a new one . The term for this is autotomy. Snakes No limbs and to external ears There is evidence for believing that snakes once had legs. Some pythons & boas still have vestigial hind legs. How many of you fear snakes? How many of you fear rattlesnakes? A graduate study was done on the human perception of snakes. 2,800 species of snakes, only 300 species are poisonous or dangerous. What are the poisonous snakes of Kansas? Prairie rattlesnake, pigmy rattlesnake, cottonmouth, western diamondback rattlesnake, timber rattlesnake, copperhead. What is the largest snake in the world? Anaconda (33 ft.), smallest is about 4 in. What does molting mean? Snakes have between 100 – 400 vertebrae 3 ways of movement in snakes 1. Lateral Undulation – most common method for crawling or swimming. Draw 2. Rectilinear or caterpillar movement – is the contract and condense of the muscles. Draw 3. Sidewinding – mostly used by??? Draw Snake Parts Nictitating membrane to cover their eyes. Forked tongue that is used for the great sense of smell. The branches of their tongue pick up particles in the air, then slide over top their Jacobson’s organs at the roof of their mouth, which are sensitive to odors. All snakes are carnivores A snake’s jaw can unhinge to engulf their prey. What are the 2 methods snakes use to kill its prey? 3 methods of injecting venom: 1. Vipers – large front retracting fangs (hypodermic) Ex. Rattlesnake, copperheads, cottonmouth 2. Elapids – small front fixed fangs (hypodermic) Ex. Cobra & coral snakes 3. Rear-fanged snakes – bite the prey & use grooved back teeth to inject the venom. Twig snakes & boom slang snakes of Africa 2 types of poisons in venom 1. Neurotoxins – affects the nervous system • Can’t breath or swallow 2. Hemotoxins – affects the circulatory system • Destroys the blood vessels (rupture) Circulatory System Two paths of blood in most terrestrial vertebrates Pulmonary Path – deoxygenated blood from heart to lungs; oxygenated blood back to heart from lungs Systemic Path – transport of oxygenated blood to body systems from the heart returning as oxygen is used up. Respiratory System Pulmonary respiration – lungs lined with air sacs called alveoli. Sacs used to increase surface area for more absorption of oxygen. Thermoregulation Ectotherm – warms its body by absorbing heat from its surroundings. This is why most lizards and snakes are found in warm climates. Reproduction Internal Fertilization Oviparous – lays the eggs outside her body. Ovoviparous – eggs are hatched inside her body. Not nourished Viviparous – bear live young that are nourished inside her body until they are developed. A snake breaks through the shell by using a egg tooth, which is lost after it breaks through the egg.