Reptiles: The First Amniotes
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Transcript of Reptiles: The First Amniotes
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-snappy-snapping-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/news/animals-news/leatherback-sea-turtle-buoyancy-vin.html
• http://video.nationalgeographic.com/video/player/animals/reptiles-animals/turtles-and-tortoises/crittercam-leatherback-turtle.html
More Sea Turtle videos• http://video.nationalgeogr
aphic.com/video/player/animals/reptiles-animals/turtles-and-tortoises/loggerhead-turtle-predation.html
• http://video.nationalgeographic.com/video/player/animals/reptiles-animals/turtles-and-tortoises/crittercam-black-turtle.html
More sea turtles• http://video.nationalgeogr
aphic.com/video/player/animals/reptiles-animals/turtles-and-tortoises/turtles-baby-predation.html
• http://video.nationalgeographic.com/video/player/news/animals-news/us-oil-spill-turtle-relocation-vin.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 SquamataSuborder Sauria: The lizards
• Usually have 2 pairs of legs• Vary from a few cm to 3 m• Geckos: short and stout/ nocturnal/ adapted
for night vision/ have adhesive disks to aid in clinging to trees and walls
Order SquamataSuborder 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/player/animals/reptiles-animals/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.nationalgeographic.com/video/player/animals/reptiles-animals/snakes/cobra-vs-mongoose-predation.html
• http://video.nationalgeographic.com/video/player/animals/reptiles-animals/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.nationalgeographic.com/video/player/animals/reptiles-animals/snakes/cobra_reproduction.html
• http://video.nationalgeographic.com/video/player/animals/reptiles-animals/lizards/cobra_repelsmonitorlizard.html
King Cobras
• http://video.nationalgeographic.com/video/player/animals/reptiles-animals/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/player/animals/reptiles-animals/snakes/snake_rattle_mating.html
Boas
• Example: anaconda– Large nonvenomous
snakes– Aquatichttp://video.nationalgeographic.com/video/player/animals/reptiles-animals/snakes/mouse_escapingfromboa.html
Anacondas
• http://video.nationalgeographic.com/video/player/animals/reptiles-animals/snakes/anaconda_stalkscapybara.html
• http://video.nationalgeographic.com/video/player/animals/reptiles-animals/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-and-meerkats/meerkat_challengingadder.html
• http://video.nationalgeographic.com/video/player/animals/mammals-animals/otters-and-meerkats/meerkat_challengingadder.html
• http://video.nationalgeographic.com/video/player/animals/reptiles-animals/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 skinNo respiratory functionsThick, dry and keratinized
EcdysisThe shedding of the reptilian skinGenerally begins in the head region and is shed in one pieceFrequency of ecdysis varies from one species to another
ChromatophoresFunction 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
• 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
• Autonomy
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/smooth-snake/
coronella-austriaca/video-06.html
locomotion
• http://arkive.org/galapagos-giant-tortoise/geochelone-spp/video-00.html
Digestion and nutrition
• http://www.arkive.org/parsons-chameleon/calumma-parsonii/video-08b.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 jawThe fangs connect to venom glands that inject venom when the viper bitesMay strike organisms of any size
Rear-fanged snakes
Possess grooved rear teethVenom is channeled into the grooves and worked into the prey to silence them during swallowingUsually do not strike
Venom GlandsModified salivary glandsMixtures of neurotoxins and hemotoxinsNeurotoxins: Attack nerve centers and cause respiratory paralysisHemotoxins: 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 well-developed 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