Transcript Reptiles and Birds

Reptiles and Birds
Unit 5 Chapter 26-2
Reddish-Brown Frilled Lizard
http://gladstone.uoregon.edu/~mkrueger/reptiles/types.htm
Reptiles

Major 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 amphibians
 Earliest fossils found are from the
Carboniferous period (360-286 mya)
 Fed on insects
 Mesozoic era (245 -65 mya)= Age of
Reptiles
 Large 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/FloraFauna/haterie_novozelandska.htm
Reproduction in Reptiles
 Oviparity
is most common among
species
 Egg encased in a secure, selfcontained 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


1.
2.
3 chambers: 2 atria and 1 partially
separated ventricle (almost 4 chambers)
Two loops: pulmonary loop and systemic
loop
Pulmonary loop carries blood to and from
lungs
Systemic loop carries blood to and from
body tissues
Respiratory System
 Large
lungs
 Alveoli (air sacs within the lungs
where gas exchange occurs)
 Reptiles, when inactive, can go for
a long time without breathing.
Nervous System
 Vision is an important sense for
reptiles
 Hearing is also important
 Jacobson’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
Thermoregulation
Thermoregulation- 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
Evolution
Birds are believed to have evolved from
small, fast-running carnivorous
dinosaurs
 Birds 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 interlock
 Preening- 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 digestion
 Aquatic birds have a thin layer
of fat that provides additional
insulation
Digestive System
Birds do not have teeth
 Food passes directly through the
esophagus to the two-part stomach
 1. 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
chambers
 Deoxygenated 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
eggs
 One or both parents incubate, or
warm the eggs
 Young, once hatched, receive
extensive parental care
Bird’s Nest
http://www.greenscreen.org/newsletter/articlesjr/images/birdsnest.gif