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Chapter 31
Reptiles and Birds
31.1: Reptiles
pgs. 796-805
Characteristics of Reptiles
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Class Reptilia
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First animals to adapt to land
Have dry scaly skin w/ claws
Have lungs
Legs at right angles from body
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Means – to creep
Provides greater support and make walking and
running on land easier
Most have 3 chambered heart; some have 4
chambered heart (crocodilians)
Characteristics of Reptiles
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Ectotherms (cold blooded)
Most are herbivores but some are carnivores
Internal fertilization (sexually)
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Lay eggs on land (amniotic eggs)
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Provides nourishment and protection to developing
embryo
Use sense organs to detect
prey or ID chemicals
What is a Reptile?
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Ectotherms (cold
Blooded) with dry,
scaly skin, with
claws on their
toes
More advanced 3
chambered hearts
(crocs have 4)
What is a Reptile?
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Amniotic eggs
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Allows reptiles to be successful on land
Evolution Reptiles
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Reptiles were the first animals
to adapt their eggs to dry
habitats
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First reptiles are from 350 mya
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Did not become common until
about 40-50 million years later
when the conditions of Earth
were drier
Mammal-Like Reptiles
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At the end of the Permian Period ~245 mya, a
great variety of reptiles roamed the Earth
Mammal-Like Reptiles
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Displayed a mixture of mammalian and
reptilian characteristics
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Dominated many land habitats
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Became extinct in just a few million years
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Replaced by another group of reptiles…
Enter the Dinosaurs
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Late Triassic and Jurassic
periods
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Two groups of large aquatic
reptiles swam in the seas
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Ancestors of modern
turtles, crocodiles, lizards,
and snakes populated many
land habitats
Enter the Dinosaurs
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Dinosaurs were
everywhere!
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Saurischia: lizard-hipped
dinosaurs
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Ornithischia: bird-hipped
dinosaurs
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Dinosaurs are the
ancestors of modern birds
Exit the Dinosaurs
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Mass Extinction 65 mya: the end of
the Cretaceous Period
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Caused by a dramatic series of natural
disasters
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Volcanic eruptions, dropping in sea
level, huge asteroid or comet
smashing into the now Yucatan
Peninsula in Mexico, etc.
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Opened up niches on land and in the
sea, providing opportunities for other
kinds of organisms to evolve
Body Temperature Control
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Reptiles are ectotherms
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They rely on behavior to help control body
temperature
To warm up, they bask in the sun
To cool down, they move to the shade
Reptile Feeding & Respiration
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Reptiles range from herbivores to
carnivores
The lungs of reptiles are spongy,
providing more gas exchange area than
those of amphibians
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Most reptiles have 2 efficient lungs to
exchange gas with the environment
Reptile Circulation
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Reptiles have an efficient double-loop
circulatory system
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Their heart contains two atria and either
one or two ventricles
Reptile Circulation
Reptile Excretion
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Urine is produced in the kidneys of
reptiles
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By eliminating wastes that contain little
water, a reptile can conserve water
Reptile Response
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The basic pattern of a reptile’s brain is
similar to that of an amphibian
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In addition to a pair of nostrils, most
reptiles have a pair of sensory organs in
the roof of the mouth that can detect
chemicals
Reptiles have simple ears and can pick up
on ground vibrations and body heat
Reptile Reproduction
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All reptiles reproduce by internal
fertilization
Most reptiles are oviparous (lay eggs
that develop outside the mother’s body)
Reptilian eggs are amniotic
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They contain a shell and membranes that
create a protected environment in which
the embryo can develop without drying out
Structure of an Amniotic Egg
Groups of Reptiles
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4 orders
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Squamata (snakes and lizards)
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Lizards live on the ground, burrows, trees or
water
Snakes - have no limbs; kill prey by
constriction or venom and swallowing whole
Chelonia (turtles)
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Protected by a 2-part shell
(dorsal-carapace & ventral-plastron)
Some are aquatic,
others are terrestrial
No teeth but powerful jaws
w/ beak-like structure
Most are herbivores
Groups of Reptiles
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4 orders (continued)
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Crocodilia (crocodiles and alligators)
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Crocodiles have long slender snouts
Alligators have short broad shouts
Fresh and salt water
4 chambered heart
Rhynchocephalia (tuatara)
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Only survivor of primitive group of
reptiles
Diversity of Reptiles
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Lizards
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Includes the largest
lizard, the Komodo Dragon
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Snakes
Includes rattlesnakes,
copperheads,
water moccasins,
& coral snakes
Diversity of Reptiles
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Carapace(Dorsal)
Turtles and tortoises
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Plastron(Ventral)
The only with hinged
shells
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Crocodilians
The only Reptiles with
4 chambered hearts
Diversity of Reptiles
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Snakes feed in a variety of ways:
Constrictors kill prey by suffocation
Venomous snakes kill prey by poisoning
Most snakes simply
grab prey and
swallow it whole
Diversity of Reptiles
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Reptiles have special sense organs:
“Pit” of rattlesnakes
allows them to detect
heat of warm-blooded
prey
Jacobson’s organ in
roof of snakes mouth
allows them to detect
odors brought in by
forked tongue
Ecology of Reptiles
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Many are in danger because of loss of
habitat
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Humans also hunt them for food, to sell as
pets, for their skins, etc.
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Some are now protected
31.2: Birds
Pgs. 806-814
Pictures of Birds
Characteristics of Birds
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Class Aves
Feathers, wings and thin
hollow bones which allow
for flight
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Keel shaped sternum
4 chambered heart
Respiratory systems consist of: lungs,
anterior and posterior air sacs
Endotherms (warm blooded)
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Able to regulate their internal body temperature
Characteristics of Birds
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Internal fertilization (sexual)
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Amniotic eggs w/ hard shell
Incubate their eggs (keep at a consistent
temperature)
Adaptations of birds
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Feathered legs and feet of ptarmigans
Modified wings and feet of penguins
Large eyes, acute sense of hearing and sharp
claws of owls
Long beaks of hummingbirds
What is a Bird?
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Class Aves
Feathers, modified
scales that provide
insulation & flight
Wings, power
provided by muscles
attached to sternum
(breastbone)
What is a Bird?
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Other adaptations for flight
include hollow bones, high
metabolism maintained by
4 chambered heart & air
sacs
Endotherm, maintains a
nearly constant body
temperature that does not
depend on environment
Form, Function, and Flight
Body Temperature Control
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Birds are endotherms (animals that can
generate their own body heat)
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They have a high rate of metabolism
compared to ectotherms (metabolism
produces heat)
A bird’s feathers insulate its body enough
to conserve most of its metabolic energy
Bird Feeding
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The more food a bird eats, the more
heat energy its metabolism can
generate
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For this reason, the phrase “eats like a
bird” is quite misleading – birds are
voracious eaters
A bird’s beak, or bill, is adapted to the type
of food they eat
Bird Digestion
Bird Respiration
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When a bird inhales, most air first enters
large posterior air sacs in the body cavity
and bones
The inhaled air then flows through the lungs
in a series of small tubes
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A complex system of air sacs and breathing tubes
ensures that air flows into the air sacs and out
through the lungs in a single direction
This constant, one way flow of oxygen-rich air
helps birds maintain their high metabolic rate and
generates enough energy for flight
Bird Circulation
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Circulation
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4 chambered hearts and two separate
circulatory loops
Structure of Bird’s Heart
Domestic pigeon
Right
atrium
Heart
Right
ventricle
Left
atrium
Left
ventricle
Complete
division
Bird Excretion
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Excretion
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Similar to those of reptiles – white, pasty
uric acid droppings
Bird Response
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Response
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Well developed sense organs
Well developed eyes that can see color
Excellent hearing
Reproduction in Birds
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Bird eggs are amniotic eggs
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They have hard outer shells
Most birds incubate their eggs until they
hatch
Diversity of Birds
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A bird’s lifestyle is determined by its
type of beak and feet.
Diversity of Birds
Diversity of Birds