Transcript Reptile Notes

Reptiles
Evolution of Reptiles
Two major forces that lead to the transition of “full-time”
life on land:
1. Increased competition for food and space in the water
2. Little competition for insects and plants on land
Reptiles evolved from Cotylosaurs. They looked like small
lizards and were successful due to the numerous
insects on land which they ate.
Cotylosaurs evolved into many new types of carnivorous
reptiles including the thecodonts that later developed
into the crocodiles, dinosaurs and the bird-like
reptiles.
What happened to the dinosaurs???
Adaptations to life on land:
1. Amniote egg- allowed reproduction
completely on land.
The egg has a protective membrane
(chorion) and leathery, porous shell for
gas exchange and holds in moisture.
The internal aquatic environment enables
embryos to survive on dry land.
The amnion surrounds and encloses the
embryo. The allantois stores waste.
The yolk sac provides a food supply.
Reptiles and Birds
Adapt to land cont.
Reproduction: Sexes separate-Fertilization internal and
water is not needed to transport sperm to egg. Most reptile
eggs are buried and the sun incubates them. After laying
their eggs, most females leave them alone to hatch.
Parthenogensis – females reproduce with out males (6
families of lizards; one snake species). No males exist.
2. Waterproof skin- Dry scales or plates made of keratin
protect the body from water loss and rough environments.
They can live in harsh conditions. Shed skin to grow.
3. External structural adaptations - limbs have claws to help
in climbing and digging, etc. Some possess suction cups
for climbing. Snakes lack limbs, but have a welldeveloped skeletal and muscle system to aid in
locomotion.
4. Respiration and circulation
Reptiles depend on lungs (full time) for gas exchange,
ribs/body wall move posterior causing neg. pressure for
air to move in; anterior movement; air moves out.
A reptile’s lungs have a large surface area. Have a
complex circulatory system ( 3-or 4 chambered heart)
Most reptiles have a 3-chambered heart: two separate
atria and one ventricle. The single ventricle pumps two
batches of blood, some blood goes to the lungs to get
oxygen, some blood with oxygen goes to body. Partial
division of ventricle.
Crocodilians have 4-chambered heart with two separate
ventricles.
Feeding and Digestion
Most reptiles are carnivores, but some are
herbivores. Many have small (backwards
pointing) teeth to hold prey while swallowing.
To make it easier to swallow prey whole,
snakes have loosely jointed jaws that can
spread apart and unhinge (kinetic jaws) to
take in their food.
Mouth esophogus stomach small
intestine large intestine cloaca
Excretion
Kidneys filter the blood to remove waste
products. Kidneys produce Uric acid, which can
be stored in a paste-like form in the bladder. This
dry waste enables reptiles to conserve water
(water is pulled out of the waste in cloaca or
bladder) and maintain homeostasis in their bodies.
In some species, water can also be stored when
available in the bladder or under the skin to be
reabsorbed later, when water is scarce.
(chuckwallas)
Some have salt glands below the eyes to get rid of
excess salt (marine iguanas)
The Brain and Senses
 Vision is the main sense in most reptiles.
 Some reptiles have tympanic membranes and
others detect vibrations through their jaw bones.
 In snakes, Jacobson’s organs in the mouth
are used to sense odors.
Temperature Control
Reptiles are ectotherms
and regulate their body
temperatures by basking
in the sun for warmth or
burrowing in the ground
to cool off.
Metabolism increases as
the body temp.
Increases, thus
increasing their activity.

Movement
 Some reptiles move with limbs sprawled to
their sides and push against the ground.
 Crocodiles have limbs rotated further under
the body and can bear more weight and
move faster.
Orders of Modern Reptiles
1. Rhynchocephlia- tuatara
2. Chelonia-turtles and tortoises
3. Crocodilia-crocodiles, alligators, camains, gharials
(gavials)
4. Squamata-lizards and snakes
1. O. Rhynchocephlia It has one “ancient” species living
today, the tuatara. It is also called the living fossil
since its order is so old. They are native to New
Zealand and resemble a large lizard.
It has a parietal eye, which is an eye covered by a thin
layer of scales. (lens, nerve and retina) It is believed to
help detect sunlight and keep the tuatara from
overheating. They have two rows of teeth on upper
jaw.
Parietal eye
2. O. Chelonia - The turtles and tortoises.
Turtles are aquatic and tortoises are
terrestrial
Turtles are streamlined for the water and
tortoises have a large dome for protection.
They have not change much in 200 million
years, since they are successful due to the
protective shell. The shell is either covered
with bony plates or leathery skin.
It has two parts: carapace ( top) and the
plastron ( bottom).
3. O. Crocodilia - Crocodiles, alligators, caimans, and
gavials (gharials)
They have changed very little over the last 200 million
years.
They are mostly nocturnal and hunt by “stealth”.
They are carnivorous and hunt with the eyes and nostrils
out of the water, while lying submerged.
Parental care is usually not present, but some species
have been known to carry young from the eggs to the
water.
Caimans are native to Central America and Gavials eat
fish in India and Burma.
Crocodiles are found in Africa, Asia and the Americas.
Alligators are found in Florida and China.
Crocodiles and Alligators
 Crocodilians have a four-chambered heart
which delivers oxygen more efficiently.
 Crocodiles have a long snout, sharp teeth,
and powerful jaws.
 Alligators generally have a broader snout
than crocodiles.
4. O. Squamata- the lizards and snakes.
They have a lower jaw which does not join directly to
the skull and have paired reproductive organs in the
males.
They live on every continent except Anartica and live
in any type of habitat. Only two lizards are
venomous.
(Gila monster and beaded lizard).
They eat insect and other small animals.
They can change colors to match their background.
They can lose their tails to escape predators and
regenerate a new one ( Autonomy).
They can fend off enemies with displays (horned
lizards).
 Lizards usually have moveable eyelids, a lower
jaw with a moveable hinge joint, and tympanic
membranes.
Snake external anatomy
• Snakes probably evolved from lizards that lived above the
ground and began to burrow as protection. Natural selection
leg to lizards without legs to move through burrows better.
Lack moveable eyelids and tympanic membranes.
Snake facts:
1. Movement - 100-400 vertebrae with ribs make this possible.
This provides a great frame for muscles. Skin and scales also
aid movement or undulation. Three types of movement in
snakes:
a. Lateral- most common, head is moved from side to
side and a wave of muscular contraction follows. (s-path, force
on the sides)
b. Rectilinear- force is on the belly scales or scutes which catch on
bark or surface area. Resembles caterpillar movement.
C. Sidewinding - done in the desert (sand) where traction is poor. A
whip-like motion of the head slings the body to the side to move.
Snake internal anatomy
2. Feeding - They are carnivores, but lack many good senses to hunt.
They locate prey with Jacobson’s organ - two pits on the roof of the
mouth which pick up chemicals from the tongue. It uses this method
to stalk prey using a chemical trail. Prey are killed using
constriction or venom. They then can swallow the animals whole.
To do this, they thrust their windpipe into the mouth in order to
breath while swallowing such a large meal and have loosely-jointed
jaws.
Most venom is injected using hypodermic-like fangs in the front, but
some have back fangs.
Two types of venom:
A. Hemotoxins - proteins that destroy red blood cells and the
platelets in blood.
B. Neurotoxins - disrupt nerve pathways which control heart and
lung functions.
3. Defense - by hiding, camouflage or warning of danger (rattles).
4. Pit vipers- find prey using heat (have pits on the side of her head)
Chapter 29
Reptiles and Birds
Chapter Diagnostic
Questions
Which is not an accurate description of a
snake’s feeding methods?
A. carnivorous
B. tongue assists in swallowing
C. venom paralyzes and digests
D. skull bones and jaw joined loosely
Chapter 29
Reptiles and Birds
Chapter Diagnostic
Questions
Which is not a feature of lizards?
A. tympanic membrane
B. lack of moveable eyelids
C. claws
D. hinged lower jaw
Chapter 29
Reptiles and Birds
29.1 Formative
Questions
Which animal does not have an amnion that
surrounds its developing embryo?
A. hawk
B. human
C. salamander
D. squirrel
Chapter 29
Reptiles and Birds
29.1 Formative
Questions
What does a snake detect with its Jacobson’s
organs?
A. heat
B. odors
C. sounds
D. visual images
Chapter 29
Reptiles and Birds
29.1 Formative
Questions
Which term describes the way reptiles
maintain their internal temperature?
A. ectothermic
B. exothermic
C. homeodermic
D. thermodermic
Chapter 29
Reptiles and Birds
29.1 Formative
Questions
What do snakes use for hearing?
A. carapace
B. jaw bones
C. plastron
D. tympanic membranes
Chapter 29
Reptiles and Birds
29.2 Formative
Questions
How do birds maintain body heat?
A. amnionically
B. externally
C. internally
D. superficially
Chapter 29
Reptiles and Birds
29.2 Formative
Questions
What organ in birds reabsorbs water from
uric acid?
A. cloaca
B. bladder
C. kidney
D. pancreas
Chapter 29
Reptiles and Birds
29.2 Formative
Questions
What is the term that means “to maintain
favorable conditions for hatching”?
A. gestation
B. incubation
C. maturation
D. pregnancy
Chapter 29
Reptiles and Birds
Chapter Assessment
Questions
What is the function of Jacobson’s Organs?
A. feeding
B. breathing
C. ejecting venom
D. sensing odors
Chapter 29
Reptiles and Birds
Chapter Assessment
Questions
Which reptile mother can keep its eggs
inside its body until they hatch?
A. turtle
B. crocodile
C. snake
D. tuatara
Chapter 29
Reptiles and Birds
Standardized Test
Practice
Which is a key adaptation that enables reptiles
to live on land?
A. Eggs have shells.
B. Eggs are fertilized internally.
C. Eggs are released in large numbers.
D. Eggs hatch outside the female’s body.
Chapter 29
Reptiles and Birds
Standardized Test
Practice
Which structure
makes the reptile
heart more efficient
than the heart of
amphibians?
Chapter 29
Reptiles and Birds
Standardized Test
Practice
Which membrane
contains food that
provides nutrition
to the embryo?
Chapter 29
Reptiles and Birds
Standardized Test
Practice
How does the cloaca enable reptiles to
maintain homeostasis?
A. It filters blood to remove waste.
B. It reabsorbs water and minerals.
C. It secretes hormones and enzymes.
D. It improves gas exchange in the lungs.
Chapter 29
Reptiles and Birds
Standardized Test
Practice
Why do birds have a large cerebellum in
their brain?
A. to control behavior
B. to coordinate visual input
C. to sense tastes and smells
D. to carry out complex movement
Chapter 29
Reptiles and Birds
Glencoe Biology Transparencies
Chapter 29
Reptiles and Birds
Image Bank
Chapter 29
Reptiles and Birds
Image Bank
Chapter 29
Reptiles and Birds
Vocabulary
Section 1
amnion
amniotic egg
Jacobson’s organ
carapace
plastron
Chapter 29
Reptiles and Birds
Vocabulary
Section 2
endotherm
air sac
feather
incubate
contour feather
preen gland
down feather
sternum
Chapter 29
Reptiles and Birds
Animation
 Amniotic Egg
 Flight
 Visualizing Feeding and Digestion