Transcript Reptiles - walker2013

Reptiles
Section 31.1
Animal Classification
Invertebrates
Sponges
Cnidarians
Worms
Mollusks
Arthropods
Echinoderms
- Order Squamata
-Snakes and lizards
- Order Crocodilia
-Crocs and gators
-Order Testudines
(or Chelonia)
-Turtles and tortoises
Animals
(cold-blooded)
Fishes
Amphibians
Reptiles
Endotherms
Birds
Mammals
Ectotherms
Vertebrates
Phylum Chordata
(warm-blooded)
What is a Reptile?
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Class Reptilia – snakes, turtles, alligators,
and lizards
Stem reptiles – early reptiles that were the
first animals to become adapted to life on
land
Evolutionary advantages reptiles have over
amphibians
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Claws
Dry skin (scales)
Scaly Skin
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Unlike the moist, thin skin of amphibians,
reptiles have a dry, thick skin covered with
scales
Scaly skin prevents the loss of body moisture
and provides additional protection from
predators
Scaly Skin
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Because of their thick skin, reptiles are
dependent on lungs as their primary organ of
gas exchange
Desert Horned Lizard
Reproduction
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Most reptiles reproduce by laying eggs on
land
Some snakes give live birth to well-developed
young
Sea turtle eggs
Gartner snake giving birth
Anaconda Birth
Reproduction
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Amniotic egg – provides nourishment to the
embryo and contains membranes that protect
it while it develops in a terrestrial (land)
environment
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The egg functions as the embryo’s total lifesupport system
Reproduction
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Parts of an amniotic egg
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1. Amnion – a membrane filled with fluid that
surrounds the developing embryo; it cushions the
embryo and prevents dehydration
Reproduction
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2. Shell – The reptile egg is enclosed in a leathery
shell
Reproduction
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3. Yolk – The main food supply for the embryo; its
enclosed in a sac that is also attached to the
embryo
Reproduction
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4. Albumen – the clear part of the egg; a source of
additional food and water for the developing
embryo
Reproduction
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5. Allantois – a membranous sac that stores the
embryo’s wastes
Reproduction
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6. Chorion – a membrane that forms around the
yolk, allantois, amnion, and embryo; the chorion
and the allantois allow gas exchange for
respiration
Reproduction
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7. Egg tooth – A reptile hatches by breaking its
shell with the horny tooth on its snout; it falls off
after hatching
Reproduction
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All reptiles have internal fertilization
Snakes and lizards have hemipenes
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Hemipenis – structure used to inject sperm into a
female
Cloaca – opening where the hemipenes is
inserted; waste also exits the cloaca
Reproduction
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Embryos develop after egg is laid
Most reptiles provide no care for hatchlings,
but female crocodiles guard their nests
Reproduction
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Most reptiles lay their eggs under rocks, bark,
and grasses; a few dig holes or form a nest
In crocodilian species, both low and high
temperatures result in females and
intermediate temperatures select for males
Reproduction
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In many turtle species, eggs from cooler
nests hatch as all males, and eggs from
warmer nests hatch as all females
Skeletal Changes in Reptiles
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Reptiles have legs that are placed more
directly under the body rather than at right
angles to the body as in amphibians
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This makes walking and running easier
Circulatory System
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Most reptiles, like amphibians, have threechambered hearts
Crocodilians have four chambered hearts that
completely separates oxygen-rich blood from
oxygen-poor blood
Circulatory System
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This separation supports the higher level of
energy use required by land animals
Ectotherms
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Reptiles do not inhabit extremely cold regions
Many species of reptiles become dormant
during cold periods in moderately cold
environments (northern United States)
How Reptiles Obtain Food
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Most turtles and tortoises are herbivores, and
those that are predators prey on worms and
mollusks
How Reptiles Obtain Food
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Snapping turtles are extremely aggressive,
attacking fishes and amphibians, and even
pulling ducklings under water
How Reptiles Obtain Food
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Lizards primarily eat insects
The Komodo dragon, the largest lizard, is
found on several islands in north of Australia
(Indonesia)
How Reptiles Obtain Food
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The komodo dragon is an efficient predator,
sometimes even of humans
Mouth is filled with deadly bacteria that is
used to kill prey
How Reptiles Obtain Food
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Some snakes have poisonous fangs
A constrictor wraps its body around its prey
Cobra vs Rat Snake
Sense Organs
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Pit organs – heat-sensitive areas that enable
snakes to detect air temperature brought by
the presence of warm-blooded animals
Sense Organs
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The tongue is used for smelling
Jacobson’s organ – a pitlike sense organ on
the roof of the mouth that picks up and
analyzes airborne chemicals
Turtles
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Order Testudines (or Chelonia)
The dorsal part of the shell is the carapace,
and the ventral part is the plastron
The vertebrae and expanded ribs of turtles
are fused to the inside of the carapace
Turtles
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Most turtles can draw their limbs, tail, and
head into their shells for protection against
predators
Turtles have powerful jaws with a beaklike
structure that is used to crush food
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Turtles
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Tortoises
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Aquatic
Eat insects and worms
(some eat birds)
Have claws
Webbed feet
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Can live up to 60 years
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Terrestrial
Eat fruits and insects
Do not have claws
Feet are not webbed;
they’re round and stumpy
Can live up to 150 years
Crocodiles
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Order Crocodilia
Crocodiles
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Long, slender, V-shaped
snouts,
Light olive brown
coloration
Found in saltwater and
estuaries
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Estuary – a mixture of
freshwater and saltwater
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Alligators
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Short, broad, U-shaped
snouts
Blackish coloration
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Found in freshwater
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Pictures of croc and gator
Crocodiles
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Crocs and gators both have powerful jaws
that can drag prey underwater and hold it
there until it drowns
Crocodiles
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Both lay eggs in nests on the ground
Unlike other reptiles, these animals stay
close to their nests and guard them
Tiger vs. Crocs
Lizards and Snakes
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Order Squamata
Most lizards have four limbs
Snakes have no limbs and lack the bones to
support limbs
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Exception are pythons and boas which retain
bones of the pelvis
The claw is known as a spur
Lizards and Snakes
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Some snakes even swim and climb trees
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Have ridges on its belly used for gripping
(like tire treads gripping the road)
Lizards and Snakes
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Snakes usually kill their prey in one of three
ways
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1. Constriction – snakes wrap themselves around
their prey
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Examples: boas, phythons, and anacondas
Boa
Lizards and Snakes
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2. Venom – These snakes use poison to paralyze
or kill their prey
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Rattlesnakes, cobras, and vipers
Lizards and Snakes
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3. Non-poisonous and non-constricting snakes get
their food by grabbing it with their mouths and
swallowing it whole
Bull Snake vs. Ground Squirrel
Cobra vs. Mongoose
Cat vs. Snake