Movement On To Land Flashcards
Land versus water
Oxygen content
Density
Temperature regulation
Habitat diversity
Early evolution of terrestrial vertebrates
origin of Tetrapods
Bony elements in paired fins
Adaptation to air breathing
Adaption to air breathing
Increased vascularization of the air-filled cavity ( becomes lungs)
Double circulation
~separate pulmonary circuit
~allows for greater absorption of oxygen
Modern amphibians (class amphibian) Diversity
Remain tied to water
~ eggs must be laid in water( moist areas)
~most larvae depend on gills for respiration
Some retain aquatic morphology throughout life
~ some have no larval stage
Gills are generally lost and lungs are activated in adults
Cutaneous respiration is very important
Thin skin loses water rapidly
Modern amphibians
General lifestyle
Adults are terrestrial
Eggs are laid in water
Larvae hatch and remain in water until metamorphosis
Metamorphosis leave water and become adults
Caecilians: order gym options (Apoda)
Elongate, limbless, fossorial Few are aquatic No lava form Borrowing No feet
Salamander:order Caudata (urodela)
Found mostly in northern temperate regions
Most small (1.5menter-15centimeters)
Has a tail
Frogs and toads: order Anura (Salientia)
W/O a a tail Tailed larval stage Larval form sometimes stays in eggs until metamorphosis Larval form protected by parent Highly evolved skeleton modification
Non-avian reptiles ( have to…)
Get away from the water The amniotic egg Other amniote advantages Amniote phylogeny The reptiles
Non-avian reptiles getting away from the water issue
Thin desiccating skin Gelatinous egg ~restricts movement of oxygen in/out of egg ~restricts rate of growth Rigid thoracic skeleton
Non-avian reptiles getting away from the water amniote solutions
Dry scary skin
Amniotic egg
Flexible thoracic skeleton
The amniotic egg (four embryonic membranes)
Chorion ~outer gas exchange membrane Yolk sac ~provides nutrients for embryo Allantois ~holds was products ~vascular to increase gas exchange Amnion ~protective fluid filled membrane around embryo
Amniotic Egg
Allows more rapid, complete development
~loss of aquatic larval stage
Adaptions
Desiccation
Product waste
Amniotic advantages
Increase thoracic ventilation
~flexible cavity
Thick waterproof skin
Thick waterproof skin advantages
Keratinization Increased lipid content between cells ~decrease loss of water Scales Results in decreased gas exchange across skin ~requires better lung respiration Some have bony plates in skin
Keratinization
Increase toughtness of skin
Order Testudines ( turtles and tortoises)
Made up of plastron and carapace
very old, successful group
Order Squamata
Extant reptiles
Some are venomous (power saliva)
Lizards
~some are ovoviviparous (embryos feed on earth)
Amniote phylogeny
Mono phyletic group Giving rise to.. ~plesiosaurs ~lepidosaurs ~turtle ~archosaurs ~synapsids
Plesiosaur
Extinct group of aquatic reptiles
Lepidosaurs
Snakes, lizards and tuataras
Archosaurs
Dinosaurs,crocodiles and birds
Synapsids
Therapsid reptiles
Give rise to mammals
Reptiles
Order testudines ( turtles
