Transcript Reptiles - Fulton County Schools

Reptiles
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Key features of Reptiles
1. Strong, bony skeletons and
toes with claws
2. Two pairs of limbs, except
snakes
3. Legs positioned vertically
for support of body and
movement on land
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External Structural
Adaptations for Land
1. Claws-aid in climbing,
digging and movement in
various terrains
2. Toes modified into
suctions cups aid in
climbing
3. Absence of limbs
 Snakes use scaly skin
and highly developed
skeletal and muscular
systems to move
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Ectothermic Metabolism
1. Regulate their temperature by
basking in the sun or seeking
shade
2. Become sluggish in very cold
temperatures
3. Intolerance to cold limits their
geographic range
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Temperature Regulation
Regulate their temp
by behavior
 Bask in sun
to speed up
metabolism
 Hide in
shade to
prevent
overheating
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Reptiles Continued
1. Dry, scaly skin, almost watertight
2. Amniotic eggs, almost watertight

Contains a water and food supply
3. Respiration through well developed
lungs

Grape shaped chamber called alveoli

Alveoli increase the respiratory
surface area for gas exchange

Strong muscles in rib cage help to
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move air in and out
Respiration
 Well developed
lungs
Tissues
involved in gas
exchange are
located inside
body
Kept moist in
even in the
driest
environments
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Heart
1. Ventricle of heart partly divided by
a septum
2. Still incomplete separation of
oxygen-rich and oxygen-poor
blood
3. Crocodiles and alligators
have a ventricle that is totally
separated into two pumping
chambers
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Circulation
Double loop circulation
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Reproduction
1. Internal fertilization
2. Many reptiles are oviparous-young
hatch from eggs
3. Some lizards and snakes are
ovoviviparous-female retains eggs
in her body until shortly
before hatching or hatching
may occur inside her body
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Excretion
 Conserve water by excreting nitrogenous
wastes in dry or pasty form as crystals of
uric acid
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1st Orders of Reptiles
Squamata
 Snakes and lizards
 lower jaw is loosely connected
to skull allowing mouth to
open wide to accommodate
large prey
 Lizards can regenerate tail,
but will not have vertebrae
 Molting occurs in both
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Squamata
1. Order consists of 5,640 species
of lizards and snakes
2. Loosely jointed upper jaw and
paired reproductive organs in
males
3. Lizards-presence of limbs
4. Common lizards- iguanas,
chameleons, skinks and geckos
5. Live everywhere except Antarctic
6. Special adaptations- agility and
camouflage
7. 2 species are venomous- Gila
monster (SW U.S.) and beaded
lizard (western Mexico)
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Squamata Continued
1. Blend with background
chameleons- remain
inconspicuous
2. Horned lizards- spiked
armor,when disturbed
they inflate,hiss and
squirt blood from eyes
3. Skinks and geckoslose their tails and
regenerate-escape
from predators
4. Most lizards are
small- .3m in length;
iguanas- 1m in length
5. Largest lizardsmonitors- Komodo
Dragon (Indonesia) 3m
(9.8 ft) in length, 140
kg (308.6 lbs)
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Adaptations of Snakes
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Movement
1. A snake has a backbone of
100 to 400 vertebrae, with
a pair of ribs attached
2. Provides the framework for
thousands of muscles
3. Interaction of bones,
muscles, and skin enables a
snake to move various
ways:
Example:
side winding
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Feeding
Snakes eat animals, but lack
structural adaptations common to other
carnivores
 Snakes do not see or hear well, have no
limbs, and teeth and small mouth cannot rip
and grind flesh
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Locating Prey
1.Snakes evolved a sense of smell which
they use to locate their prey
2.Flicks its forked tongue to gather
chemicals from the environment
3.Transfers chemicals to two pits in the
roof of the mouth-Jacobsons organ
where nerves are highly sensitive to
the chemicals
4.Some snakes inject toxic venom by
biting with fangs and injecting
5.Hemotoxins-attack the circulator
system-disrupt the clotting of blood.
6.Neurotoxins-disrupting the nerve
pathways-dangerous to respiratory and
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heart functions.
Reproduction
1. Most male snakes rely
on the scent of
female snakes of heir
own species
2. Before mating, a male
and female snake may
glide alongside by
side, with the male
stroking the female
with his chin and
flicking his tongue
over her body
3. Fertilization is
internal
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Reproduction Continued
1. Most snakes are oviparous
2. Female lays eggs that
hatch outside her body
3. To break out a hatchling
uses a special tooth which
is lost soon after
4. Other snakes are
ovoviviparous
5. Female carries the eggs
in her body
throughout development
6. Young are born live
7. All newborns must fend
for themselves, relying on
their many specialized
adaptations for survival
on land
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Defense
1. Natural selection resulted in modifications for
defense.
2. Camouflage is beneficial for both seeking prey and
hiding from predators.
3. Many snakes are green and blend with foliage
4. Others are brown and hide against the bark of
trees
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Swallowing and Digesting Prey
1. A snakes upper and
lower jaws are
hinged and move
independently.
2. when unhinged, the jaws
stretch to allow the
mouth to open extremely
wide.
3. While swallowing it whole
the snake thrusts its
windpipe into the throat,
allowing the snake to
breathe
4. The process of can take
several hours
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Defense Continued
1. Some ward off
danger by rapidly
changing body
shape
2. Extending a hood
like cobras
3. Some hiss
4. Others make
mechanical noises
5. Such as the rattle
of the rattlesnake.
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2nd Order of Reptiles
Chelonia
 Turtles and tortoises
 Hard bony shell-dorsal
is carapace and
ventral is plastron
 Lack teeth, but have beaks
 Many herbivores but some are
carnivores
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Chelonia
1. Order consists of about 265
species of turtles and
tortoises
2. Tortoise are terrestrial
3. Turtles live in water
4. Body covered by a shell made
of hard plates- 2 parts- a
carapace and plastron
5. Retractable head
6. Forelimbs of a marine turtle
have evolved into flippers and
freshwater turtles have
webbed toes
7. Migratory behavior of sea and
river turtles
8. Returns to land to lay eggs 25
3rd Order of Reptiles
Crocodilia
 Crocodiles and alligators
 Most closely related
to dinosaurs
 Aggressive carnivores
 Care for their young after
hatching
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Crocodilian
1. Order composed of 20 species
of large lizard-shaped
reptiles- crocodiles, alligators,
caimans and gavials
2. Crocodilians live in or near
water in tropical/ subtropical
regions of the world
3. Crocodiles-nocturnal animals;
Africa, Asia and Americas
4. Alligators-China and southern
U.S.
5. Caimans-Central America,
some in Florida
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1. Carnivorous
2. Eyes on head,
nostrils on top of
snout
3. See and breathe
while in water
4. Parental careboth parents care
for young by
carrying in jaws
until development
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4th Order of Reptiles
Rhynchocephalia
Tuataras
Two species native to
New Zealand
Most active at low
temperatures
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Rhynochocephalia
1. Only living species-New
Zealand
2. Resembles a large lizard
about 60 cm long
3. Parietal eye-functions
as a thermostatprotects from
overheating
4. Active at low
temperatures, feed at
night on insects, worms
and small animals
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310 million
years ago…
reptiles were the
first vertebrates
to make the
complete
transition to
life on land
 An increase in
competition for food
and space among all
the life-forms in
aquatic environments

Limited competition for
the insects and plants
that could be used as
food on the land
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Adaptations to Land
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Adaptations to Land
Amniotic Egg
Legs
Lungs
Scales or plates
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Amniotic Egg
1. An egg with a
protective membrane
and a porous shell
enclosing the developing
embryo
2. Egg forms a “nursery”
to protect the embryo
3. Egg derives its name
from the amnion, the
thin membrane enclosing
the salty fluid in which
the embryo floats
4. Yolk sac encloses the
yolk, a protein rich
food supply for the
developing embryo
5. Allantois stores the nitrogenous wastes produced
by the embryo until the egg hatches
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1. The chorion regulates the
exchange of oxygen and
carbon dioxide between the
egg and the outside
environment
2. Amniote egg is surrounded
by a leathery shell that may
be hard in some species
(Birds) because of the
presence of calcium
carbonate
3. The male places the sperm
inside the female before the
shell is formed. This is
called internal fertilization,
makes water transport of
sperm unnecessary
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Origin and Evolution
 From the studies of
fossils and
comparative
anatomy, biologists
infer that reptiles
arose from a group
of ancestral reptiles
called cotylosaurs,
which lived about
310 million years
ago.
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The End
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