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Reptiles: The First Amniotes Amniotic egg • Have embryonic membranes that protect the embryo from desiccation, cushion the embryo, promote gas transfer and store waste materials • Have leathery or hard shells that protect the embryo, albumen that cushions and provides moisture and nutrients fro the embryo, has a yolk that supplies food to the embryo • Distinguishes the reptiles, birds and mammals from other vertebrates Amniotic egg • Amnion: encloses the embryo in a fluid filled sac and protects against shock and desiccation • Chorion: aids in gas exchange • Allantois: stores N-waste • Yolk: embryo develops at the surface 7 examples of reptiles Subclass #1: Anapsida • Turtles represent this lineage • Form of their skull and shell is recognizable in 200-million year old fossils and as far back as 245 million year old rocks in South Africa Galapagos Tortoise • Vulnerable • Can be up to 880 lbs and 6 ft long • Can live up to 100 yrs in the wild and 170 yrs in captivity • #s are decreasing due to hunting, habitat destruction and the introduction of non-native species Subclass #2: Diapsida • Include modern snakes, lizards and tuataras (Lepidosauromorpha) • Archosauromorpha (a subgroup) includes dinosaurs and most are extinct • Archosaurs: Include crocodilians and birds (dinosaurs closest living relatives) Subclass #3: Synapsida • No members of this group survive today • Important because therapsids (a group of synapsids) gave rise to the mammals Characteristics of reptiles • Dry skin with keratinized epidermal scales • Keratin is a resisitant protein used for protectiveness and prevents water loss • Live on all continents except Antartica Order Testudines • • • • Turtles 300 species of turtles Have long life spans Large tortoises may live in excess of 100 years • Tortoises are entirely terrestial Order Testudines • All turtles are oviparous (lay eggs that develop outside of the body) • Females use their hindlimbs to excavate nests in the soil • They lay and cover with soil clutches of 5 to 100 eggs • Development takes 4 weeks to a year and the parent does not attend to the eggs during the time Snapping turtle • One of the largest freshwater turtles • Makes a hissing sound when in danger or feels threatened • Has a powerful jaw and a highly mobile head • Live up to 47 yrs in captivity and up to 30 years in the wild • Omnivores • Live in shallow ponds, lakes and streams • A popular ingredient in turtle soup Alligator snapping turtle • Vulnerable • Largest freshwater turtle in North America • Can be up to 249 lbs • Average is 175 lbs and 26 in in length • http://dsc.discovery.com/v ideos/dirty-jobs-snappysnapping-turtles.html Sea Turtles • Endangered • Marine reptiles • Found everywhere except in the Artic • Almost always submerged so they have an anaerobic system for breathing • Hawksbill sea turtle Sea Turtle continued • Have large lungs so they can have rapid gas exchange • Emerge from the water to breed • The female will lay eggs under the sand • The temp of the sand determines the gender of the offspring • Green sea turtle More sea turtles • The lighter the sand, the increase of temperature, the lower the incubation time females • Immune to the sting of the box jellyfish • Flatback sea turtle Lights, Camera, Sea Turtles • http://video.nationalgeogr aphic.com/video/player/ne ws/animalsnews/leatherback-seaturtle-buoyancy-vin.html • http://video.nationalgeogr aphic.com/video/player/an imals/reptilesanimals/turtles-andtortoises/crittercamleatherback-turtle.html More Sea Turtle videos • http://video.nationalgeogr aphic.com/video/player/an imals/reptilesanimals/turtles-andtortoises/loggerheadturtle-predation.html • http://video.nationalgeogr aphic.com/video/player/an imals/reptilesanimals/turtles-andtortoises/crittercam-blackturtle.html More sea turtles • http://video.nationalgeogr aphic.com/video/player/an imals/reptilesanimals/turtles-andtortoises/turtles-babypredation.html • http://video.nationalgeogr aphic.com/video/player/ne ws/animals-news/us-oilspill-turtle-relocationvin.html American Boxing turtles • Usually kept as pets • Can live up to 50 years • Omnivores • Dig holes to winter in • Eat invertebrates and vegetation Turtles vs. Tortoises • Webbed feet with long claws • Found in Africa & America • Flat shells • Dwells in water • 20-40 years • Kept as pets • Short and sturdy feet with bent legs • Found in asia and africa • Large dome shells • Dwells on land • 80-150 years • Not kept as pets Turtles vs. tortoises Carapace, plastron Carapace: the dorsal portion of the shell, keratin cover the bones of the carapace Plastron: the ventral portion of the shell, keratin cover the bones of the plastron Alligator facts • • • • • • Transparent third eyelid gives underwater protection. 80 teeth; 40 top, 40 bottom Teeth are conical; used for grabbing and holding, not for cutting. Young alligators can replace teeth every year or so. Mother 'gators will care for their young for up to two years. Use feet to swim slow and to keep balance in water; use tail to swim fast • 4-chambered heart • Integumentary sense organs on jaws, nose, around eyes and on upper palate • Egg tooth; a toughened bit of epidermis on the tip of a hatchling’s nose, which allows it to break out of its egg; it is absorbed a few weeks after hatching Alligator vs. Crocodile • • • • • Hibernate Males up to 14 ft More docile Rounded snout Show fewer teeth when the mouth is closed • Fresh water • Grayish black • • • • • Don’t hibernate Males 19+ ft More aggressive Pointed snout Show more teeth when the mouth is closed • Brackish water • Light tan to brown Alligators vs. Crocodiles Order Sphenodonitda • Tuaturas • Superficially unchanged from their extinct relatives that were present at the beginning of the Mesozoic era • Present only on remote offshore islands and are protected by New Zealand law • Feed on insects or occasionally small invertebrates at dusk and dawn Order Squamata • Ovipoarous: organism lays eggs that develop outside the body of the female • Ovoviviparous: organisms lay eggs that develop within the female reproductive tract and that are nourished by food stored in the egg • Viviparous: organisms with eggs that develop within the female reproductive tract and are nourished by the female Order Squamata Suborder Sauria: The lizards • Usually have 2 pairs of legs • Vary from a few cm to 3m • Geckos: short and stout/ nocturnal/ adapted for night vision/ have adhesive disks to aid in clinging to trees and walls Order Squamata Suborder Sauria-iguanias • Robust bodies, short necks, and distinct heads • Marine iguanas in the Galapagos and the flying dragons of Southeast Asia Flying Dragon • http://video.nationalgeographic.com/video/p layer/animals/reptilesanimals/lizards/flying_reptiles.html Chameleons • Live mainly in Africa and India • Adapted to aboreal lifestyles • Use a long, sticky tongues to capture insects • Can change color in response to illumination, temperature or their behavioral state Gila monsters • Gila monsters and the Mexican beaded lizard are the only venomous lizards • Venom is released into grooves on the surface of teeth and introduced into prey as the lizard chews Suborder Serpentes—The snakes • About 2900 species • About 300 species are venomous • Most are oviparous • Upper and lower jaws are loosely joined so that each half can move independently of each other King Cobras • World’s longest venomous snakes • Can be up to 18.5 feet and 13 pounds • Skin: olive green, tan or black • Cream belly and smooth scales King cobras • Can live up to 20 years • Use their forked tongue to pick up the scent of prey then finds its location by flicked its tongue and using its eye sight • http://video.nationalge ographic.com/video/pl ayer/animals/reptilesanimals/snakes/cobravs-mongoosepredation.html • http://video.nationalge ographic.com/video/pl ayer/animals/reptilesanimals/snakes/cobra_ eatsratsnake.html More king cobras • Cobra swallows its prey whole • Venom can kill a healthy human in 30-45 minutes • Reproduction: female builds a nest to incubate its eggs (20-40) when they are about to hatch the female leaves and gets prey so that it is not tempted to eat the young • http://video.nationalgeogr aphic.com/video/player/an imals/reptilesanimals/snakes/cobra_repr oduction.html • http://video.nationalgeogr aphic.com/video/player/an imals/reptilesanimals/lizards/cobra_repe lsmonitorlizard.html King Cobras • http://video.nationalge ographic.com/video/pl ayer/animals/reptilesanimals/snakes/cobra_ babyhunt.html Garter Snake • Most widely distributed snake in North America • Meat eaters • Follow pheremone scented trails to find other snakes • Reproduction: stop eating for 2 weeks before mating, the female attracts male with pheremones, the female can store the males sperm for years, the young incubate in the lower abdomen and snakes give birth to live young, 3-80 are born at a time Sidewinder rattlesnake • Venomous • Move in a J-shape • Nocturnal in the hot months • Diurnal all the rest of the year • Homeothermy when first born Sidewinder • http://video.nationalgeographic.com/video/p layer/animals/reptilesanimals/snakes/snake_rattle_mating.html Boas • Example: anaconda – Large nonvenomous snakes – Aquatic http://video.nationalgeogr aphic.com/video/player /animals/reptilesanimals/snakes/mouse_ escapingfromboa.html Anacondas • http://video.nationalgeographic.com/video/p layer/animals/reptilesanimals/snakes/anaconda_stalkscapybara.ht ml • http://video.nationalgeographic.com/video/p layer/animals/reptilesanimals/snakes/anaconda_bitesman.html pythons • • • • Nonvenomous snakes Ambush predators Constrictors Lay eggs Vipers • Venomous snakes • Long hinged fangs which are used to inject venom into their prey • Nocturnal • Ambush • Give birth to young Snake videos • http://video.nationalgeographic.com/video/player/ animals/mammals-animals/otters-andmeerkats/meerkat_challengingadder.html • http://video.nationalgeographic.com/video/player/ animals/mammals-animals/otters-andmeerkats/meerkat_challengingadder.html • http://video.nationalgeographic.com/video/player/ animals/reptilesanimals/snakes/cobra_reproduction.html Suborder Amphisbaenia—Worm Lizards • About 135 species • Specialized burrowers that live in soils in Africa, South America, the Caribbean and the Mideast • Legless and their skulls are shovel shaped • Feed on worms and small insects and are oviparous Tyrannosaurus Rex • Found in western north America • 67 to 65.5 million years ago • Bipedal carnivore • 42 ft in length and 68 metric tons • Skulls up to 5 ft in length • Endothermic • Could eat 500 pounds of meat in one bite Maiasaurs • • • • • • • • • Live in herds Bipedal or quadpedal Herbivores 3-4 tons Eats 200 lbs of food per day 25-30 feet Duck billed Lived 74 million years ago Found in what is now Montana Eoraptor • Small meat eater • 231 million years ago • 22 pounds and 3 feet long • omnivore Seismosaurus • 110 feet long • 154-144 million years ago • Walked on 4 legs • Found in New Mexica • “earth shaking lizard” Triceratops • 65 million years ago • Herbivore • 3 horns Veloceraptors • Bipedal carnivore • 75-71 million years ago Troodon • 75 – 65 million years ago • “Wondering tooth” • 6.5 feet in length • 130 pounds • Found in Wyoming, Texas, New Mexico Ankylosaurus • • • • 13,000 pounds Armoured 30 feet 66-65 million years ago Microraptor • 2.2 pounds • 40 cm long • 4 winged Reptile skin No respiratory functions Thick, dry and keratinized Ecdysis The shedding of the reptilian skin Generally begins in the head region and is shed in one piece Frequency of ecdysis varies from one species to another Chromatophores Function in sex recognition and thermoregulation Support and Movement Secondary palate • Partially separates the nasal passage from the mouth cavity. • An adaptation for breathing when the mouth is full of food or water • Longer snouts allow for a greater sense of smell Secondary palate Support and Movement Reptile Vertebrae • First two cervical vertebrae provide greater movement for the head and facilitates nodding • A variable number of other cervical vertebrae provide additional neck flexibility Reptile Vertebrae Support and movement Ribs • Highly modified • Ribs of snakes have muscular connections to the large belly scales to aid locomotion Ribs Support and Movement • Autonomy • Tail loss • When lizards are grasped by the tail, caudal vertebrae can be broken and a portion of the tail is lost • The lizard can later regenerate the lost portion of the tail Locomotion in reptiles • In primitive reptiles, the body is slung low between paired, stocky appendages • The limbs of other reptiles are more elongate and slender and are held closer to the body • Many prehistoric reptiles were bipedal • http://www.arkive.org/smoothsnake/coronella-austriaca/video-06.html locomotion • http://arkive.org/galapagos-gianttortoise/geochelone-spp/video-00.html Digestion and nutrition • http://www.arkive.org/parsonschameleon/calumma-parsonii/video08b.html Digestion and nutrition • Most reptiles are carnivores • The tongues of turtles aid in swallowing • Some lizards and the tuatara have sticky tongues for capturing prey • The tongue extension of chameleons exceeds their body length • The bones of the upper jaw are movable in the skull of the snake and ligaments loosely join the halves of the jaw so they can move independently of each other Feeding vipers Possess hollow fangs in the upper jaw The fangs connect to venom glands that inject venom when the viper bites May strike organisms of any size Rear-fanged snakes Possess grooved rear teeth Venom is channeled into the grooves and worked into the prey to silence them during swallowing Usually do not strike Venom Glands Modified salivary glands Mixtures of neurotoxins and hemotoxins Neurotoxins: Attack nerve centers and cause respiratory paralysis Hemotoxins: break up blood cells and attack blood vessel linings Snake venoms and treatment for it • The best treatment for a venomous snake bite is the get to the emergency room immediately Circulatory system in reptiles • Based on the same as the amphibians • The blood must move under higher pressures to reach distant body parts since they are larger then amphibians Gas Exchange • Reptiles exchange gases across internal respiratory surfaces to avoid losing large quantities of water • A larynx is present but no vocal cords • Lung chambers provide a large surface area for gas exchange Lung ventilation • Ribs move and the body wall expands the body cavity decreasing the pressure in the lungs drawing air into the lungs • Air is expelled by elastic recoil of the lungs and forward movement of the ribs and the body wall which compress the lungs • Turtles exhale and inhale by contracting their lungs Temperature regulation • Most use external sources to regulate their body temps so they are ectotherm • Lizards: to warm themselves it orients themselves at a right angle to the sun’s rays, burrows, etc. to reduce the conduction from warm surfaces…in hot climate they are nocturnal • Chromatophores can regulate body temp • Enter into torpor to decrease metabolic rates Temperature regualtion Hibernacula • A common site of hibernation for organisms that are usually solitary but hibernate in the winter together • Body temp is not regulated • If winter is too cold, the reptile can freeze and die Nervous system • Larger then amphibians due to an improved sense of smell • Optics lobes and cerebellum are enlarged due to a reliance on vision and coordinated muscle functions Chameleons and binocular vision • Eyes swivel independently of each other • Initially images are kept separate but when the prey is seen then they see is as one image Reptilian eyes • Reptiles rely heavily on their sense of sight • The have many cones in their eyes so they probably have welldeveloped colored vision • Median eye can be used for differentiation of light and dark and used for orientation to the sun Reptile ears • Ears of snakes detect vibrations • Snakes can detect airborne vibrations Excretion and Osmoregulation • Require kidneys capable of processing wastes with little water loss • Excrete uric acid • Urinary bladder reabsorb water • Can store large quantities of water in lymphatic spaces under the skin or in the urinary bladder • Possess salt glands below the eyes for ridding the body of excess salt Reproduction • Internal fertilization • Sperm may be stored for up to 4 yrs in some turtles and up to 6 yrs in some snakes • Parthogenesis: no males have been found, a form of asexual reproduction • Courtship: head bobbing reveals bright colors on the throat, tail-waving displays courtships • Vocalization is only important in crocodiles • American alligators: if nest occurs at or below 31.5 degrees then the result is a female and if the temps are between 32.5 and 33 then a male is the result
