C H. 31: R EPTILES AND B IRDS Section 31.1: Reptiles

W HAT IS A R EPTILE First animals to become adapted to life on land Are able to complete their life cycles entirely on land Have thick, dry, scaly skin Prevents loss of moisture Protects from predators Because gas exchange can not take place through thick skin, they depend on lungs entirely. Legs placed under body instead of at right angles Provides greater body support and allows them to move better on land Better chance of catching prey or avoiding predators Have claws that allow them to obtain food and protect them

REPTILES Some reptiles have four chambered hearts Most have 3 chambered hearts like amphibians 4 chambers completely separates oxygenated from deoxygenated blood Adaptation allows for more energy for land life Reproduce on land Lay eggs on land Babies look just like adults, just smaller Evolution of the “amniotic egg” liberated reptiles from being near water. Provides nourishment and protects it from drying out

A MNIOTIC EGG CLOSE UP Has leathery covering to prevent from drying out Has amnion Membrane filled with fluid that surrounds the embryo Cushions embryo and prevents dehydration Yolk- main food supply for developing embryo Chorion- membrane that allows for gas exchange Allantois- sac that collects the embryo’s waste products. Is left behind when it hatches Egg tooth- used to break egg when time to hatch. Falls off shortly after hatching

REPTILES All reptiles have internal fertilization most reptiles provide no protection for eggs Reptiles are ectotherms Body temp. depends on the surrounding temperature Can control body temp. by behaviors Turtle basking in the sun or going to shade at mid day Don’t inhabit really cold or hot regions

H OW REPTILES OBTAIN FOOD Some, like most turtles, are slow. They are herbivores Snapping turtles are very quick and attack fish and amphibians Most lizards are carnivores They may appear slow but are capable of quick bursts of speed Komodo dragon able to eat humans

B IRDS Like reptiles, birds have clawed toes and scales on their feet Fertilization is internal They produce amniotic eggs Only organism with feathers Modified scale Provides insulation Allows for flight Bird uses its beak to rub oil on feathers Keeps them water proof Shedding of feathers is called molting

BIRDS Birds have wings Second adaptation for flight Modification of front limbs Powerful flight muscles attached to the sternum Flight requires high levels of energy Have four chambered heart Bird chick can have a heart rate of 1000 beats per min. Moves oxygenated blood to body cells quickly Have a unique lung set up to allow for a lot of oxygen to reach the cells. See pg. 854

BIRDS Birds are endotherms They can maintain their own body heat like us Allows them to live in all environments Birds use amniotic eggs They build nests to take care of young Fewer eggs Incubate eggs (sit on them to keep warm)

D IVERSITY OF BIRDS Birds have all kinds of different traits depending on the environment they live in Large eyes of the owl Webbed feet of a duck Flightless like ostrich or penguin Different beak shapes depending on food they eat

O RIGIN OF BIRDS Some scientists believe they evolved from a branch of dinosaurs that didn’t become extinct Archaeopteryx is the first known fossil of birds