Download - Reptiles and Birds
Reptiles and Birds
Unit 5 Chapter 26-2
Reddish-Brown Frilled Lizard
http://gladstone.uoregon.edu/~mkrueger/reptiles/types.htm
ReptilesMajor characteristics:
1. Terrestrial
2. Do not need to reproduce in water
3. Have an amniotic egg to provide embryo with moist environment
4. Watertight skin (made of keratin)
5. Use lungs to respire
6. Excrete uric acid (solid)
Reptile Evolution
Reptiles evolved from amphibiansEarliest fossils found are from the
Carboniferous period (360-286 mya)Fed on insectsMesozoic era (245 -65 mya)= Age of
ReptilesLarge reptiles were dominant (dinosaurs)
Extinction of Dinosaurs
Asteriod-Impact hypothesis: asteroid hit Earth, caused huge clouds of dust, blocking sunlight (evidence=soil containing iridium)
http://www.nmnh.si.edu/paleo/blast/
Four Modern Orders of Reptiles Turtles and tortoises Lizards and snakes Tuataras Crocodillians
*More than 6,000 species of reptiles exist today
Tuatara
http://www.volny.cz/martin.sliva/NovyZeland/Flora-Fauna/haterie_novozelandska.htm
Reproduction in Reptiles
Oviparity is most common among species
Egg encased in a secure, self-contained aquatic environment
Amniotic eggs provide protection, nutrients, waste storage
Amniotic Egg
http://uk.encarta.msn.com/media_461517464_761562707_-1_1/Amniotic_Egg.html
Circulatory System
3 chambers: 2 atria and 1 partially separated ventricle (almost 4 chambers)
Two loops: pulmonary loop and systemic loop
1. Pulmonary loop carries blood to and from lungs
2. Systemic loop carries blood to and from body tissues
Respiratory System
Large lungsAlveoli (air sacs within the lungs
where gas exchange occurs)Reptiles, when inactive, can go for
a long time without breathing.
Nervous SystemVision is an important sense for
reptilesHearing is also importantJacobson’s organ- specialized sense
organ located in the roof of the mouth of reptiles, sensitive to odors
-tongue transfers chemicals to Jacobson’s organ for it to interpret
ThermoregulationThermoregulation- control of body
temp.Ectotherms- warms its body by
absorbing heat from its surroundings (fish, amphibians, reptiles)
Endotherms- have a rapid metabolism that generates heat needed to warm the body (mammals and birds)
Birds
Birds (Class: Aves)
Major Characteristics:
1. Feathers (insulation, flight)
2. Wings (modified forelimbs)
3. Lightweight rigid skeleton
4. Endothermic metabolism
5. Beak
6. Oviparity
EvolutionBirds are believed to have evolved from
small, fast-running carnivorous dinosaursBirds had to evolve anatomical,
physiological and behavioral adaptations for life in the air
1. Wings
2. Hollow bones
3. Feathers
Feathers
Feathers are modified scales: facilitate flight, conserve body heat.
Barbules on feathers interlockPreening- birds use their beaks to
rub their feathers with oil secreted by the preening gland.
Birds molt their feathers
Structure of a Feather
http://numbat.murdoch.edu.au/Anatomy/avian/fig2.6.GIF
Thermoregulation
Birds are endothermic Have a high metabolism: rapid
breathing and digestionAquatic birds have a thin layer
of fat that provides additional insulation
Digestive SystemBirds do not have teethFood passes directly through the
esophagus to the two-part stomach1. 1st chamber= proventriculus (acid,
enzymes break down food)2. 2nd chamber= gizzard (kneads and
crushes food)Small intestine- further broken down
and absorbed
Excretion
Kidneys excrete uric acid (solid nitrogenous waste) helps to conserve waste
Circulatory System
4 chambersDeoxygenated and oxygenated
blood is kept separate.Birds have rapid heart rates
Example: hummingbird’s heart beats 600 times per minute
Bird’s Heart
Nervous system
Highly developed cerebellum to control balance, and flight
Highly developed sense of vision: can discriminate color, depth
Hearing is important to songbirds and nocturnal species
Reproduction
Lay eggsOne or both parents incubate, or
warm the eggsYoung, once hatched, receive
extensive parental care
Bird’s Nest
http://www.greenscreen.org/newsletter/articlesjr/images/birdsnest.gif