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