Class Reptilia

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2

History

• Reptiles are the evolutionary base for the rest of the

tetrapods

.

• Early divergence of

mammals

from reptilian ancestor.

• Early reptiles arose from

insectivores

.

amphibian

ancestor and were small, lizard-like 3

• • •

Class Reptilia

•

Scales

• Amniotic

egg

• One occipital condyle

Ectothermic Three

chambered heart – Alligators have

4 Claws

4

Ectothermic

5

• directly

Common Features

• Positioning of legs more

under

animal (more support).

Paired

limbs with

five

toes. –

Adapted

for running, climbing, swimming.

–

Absent

in snakes.

6

Common Features

• • Body covered with horny

epidermal

scales made from protein

keratin reduce

and provide

protection

.

. – Scales serve to water loss – Reptiles

molt

they grow.

as

Jaws

adapted to biting/tearing. 7

8

internally

turtles).

partially

Common features • Respiration through protected and moistened (a moist cloacal surface in some • Most reptiles have a 3 chambered heart with a divided ventricle. – No

mixing

of blood from lungs with deoxygenated blood.

– Crocodiles have

4

chambers and a unique feature: cog teeth.

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Common features

• Excretory waste =

uric acid

(doesn’t waste water) •

Brain

= first cerebral cortex (capable of

reasoning

, planning, perception) • Still ectothermic – Must live in much

less favorable

conditions or hibernate.

– Being ectothermic enables an organism to survive on food than an endothermic organism.

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• • Reproduction

Internal

fertilization: gametes not subject to desiccation.

Amniote

egg = significant evolutionary breakthrough.

– Egg covered by

tough

compartmentalize the , water-resistant, leathery or calcerous shell.

– Extraembryonic membranes

interior

for several functions.

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Amniote Egg

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Amniote Egg

• • • •

Chorion

= hard covering permeable to respiratory gases but not water.

Allantois

= functions in gas exchange and a storage reservoir for metabolic waste.

Amnion

= fluid-filled sac acts as cushion for embryo and prevents desiccation.

Yolk sac

= food for embryo; eliminates need for larval stage.

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Reptile Skulls

• Except for turtles, all reptiles have

two

temporal openings in the skull.

• These openings have allowed for attachment and expansion of the

jaw muscles.

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Reptile Skulls

•

Anapsid

– No opening • Synapsid – One opening •

Diapsid

– Two openings • Euryapsid – One small opening 15

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Subclass Anapsida Order Testudines • 260 species of turtles/tortoises •

Oldest

group of reptiles (225 mya) • Protective body shell – Encases

vital

organs – Provides some

protection

to head/limbs – Composed of bony scales – 2 parts: upper

plates

covered by horny epidermal

carapace

, lower

plastron

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Primitive features – Loss of body-wall

muscles

– Ribs/trunk vertebrae

fused

to carapace –

Lack

food teeth; hard

beak

grab and tear

Subclass Anapsida Order Testudines

•

All

lay eggs on land.

• Third eyelid =

nictitating

membrane.

• Longest

living

wild)!

vertebrates (100+years in 19

TURTLES & TORTOISES

• Only reptile

with

shell • Only reptile WITHOUT

TEETH http://www.perlgurl.org/archives/2006/05/hawaiian_honu_the_green_sea_turtle.html

http://www.carcosa.net/jason/blog_images/2005/07/04/african-spurred-tortoise.jpg

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Turtle Shell

Carapace Plastron 21

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Box Turtle

Terrapene

• Adapted to live on

land

– Feet not

webbed

– High

domed

shell – Safe 23

Red-Eared Slider

Trachemys

•

Red

stripe behind eye • Live in or near

water

– Ponds – Slow moving water • Pets • Carry

Salmonella

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Snapping Turtle

Chelydra

• Live

in

water • Lay eggs on land • Long

tail

• Muscular

limbs

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Giant Tortoise Lifespan 150 Years 27

Leatherback Sea Turtle

• 6 feet long • 1,400 pounds 28

• Dinosaurs • Snakes • Lizards • Crocodilians • Birds

Diapsids

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Subclass Diapsida

• Superorder Lepidosauria – Order

Squamata

• 4675+ species of lizard • 2700+ species of snakes • 140 species of amphisbaenians –

Limbless

, burrowing animals –

Vestigial

eyes under skin 30

Order Rhynchocephalia • 2 species of Tuatara •

Solitary

, nocturnal, burrowing animal

Order Squamata

• Kinetic skull –

Movable

joints • Lizards • Snakes • Dinosaurs 32

Order Squamata

• Most successful, diversified of living reptiles.

• Occur in most habitats of world.

• Lizards: –

Legs

, eyelids,

ear

openings – Halves of lower jaw

united

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Geckos

• • Small lizards

Adhesive

toe pads 34

Gecko Toe Pads

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Wall Lizard

Lacerta

• Color is

variable

• Slender body • Small

scales

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AUTOTOMY

• Self

amputation

to escape predators • • Can’t regrow

Costly

; lose muscle/stored fat

http://www.californiaherps.com/lizards/images/ecprincipis1dn.jpg

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Texas Horned Lizard

•

Spines

for protection • • Eats ants

Endangered

species 38

Gila Monster

•

Poisonous

• Not very aggressive lizard 39

Green Iguana

• • Ornamental

crest

• Five feet long • Tropical rainforest – Mexico – South America

Omnivores

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Chameleons

•

Arboreal

- live in trees • Africa and Madagascar • Catch insects with

tongue

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Komodo Dragon

• Attack and eat

humans

• 10 feet long • 300 pounds • Indonesia 42

Snakes

•

Elongated

derivative of lizard (increased vertebrae, not lengthening of segments) •

Lack

limbs, eyelids, ear openings • Jaw bones are

loosely

swallowing of large prey united to allow • Throat and windpipe are at

separate

ends of mouth to allow breathing while eating • • Can be

venomous Tongue

to smell, some have sense body heat (hemotoxin/neurotoxin)

heat pits

to

Snakes

• No legs • • No external ears

Jacobson’s organ

• – Sense smell with aid of tongue • Cornea of eye protected with a

spectacle

– transparent membrane

Skull

bones loose – Swallow large prey 44

JACOBSON’s ORGAN

• An extrasensory organ in the

roof

of a snake's mouth • Sharpens its sense of

smell

. • Two hollow, highly sensitive

saclike

• Allows it to track both

prey

structures and potential

mates

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http://www.kwic.com/~pagodavista/schoolhouse/species/herps/snktonge.htm

HEAT SENSING ORGAN

• “Pit" organ located between the

eye

and the

nostril

on each

side

of the head. • Detects heat given off by

warm-blooded

prey 46

http://www.kwic.com/~pagodavista/schoolhouse/species/herps/snktonge.htm

Swallow Prey

47

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http://www.thematzats.com/snakes/images/squeeze.gif

•

Wrap

Constrictors

around prey and kill by suffocation • Ex: Boa constrictors

http://www.eastrock.org/brazil/images/bra19.jpg

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•

VIPERS

Inject

venom with large

movable

fangs Ex: rattlesnakes, copperheads, water moccasins 50

Images from: http://www.worsleyschool.net/science/files/rattle/snakes.html

•

ELAPIDS

Inject

fangs venom with small

fixed

(non-movable) Ex: cobras, kraits, coral snakes 51

http://www.kidsturncentral.com/animals/cobra.htm

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Snake Venom

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Copperhead

Agkistrodon

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Cottonmouth or Water Moccasin

Agkistrodon

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Western Diamond Backed Rattlesnake

Crotalus

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Prairie Rattlesnake

Crotalus

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Timber Rattlesnake

Crotalus

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Black Rat Snake

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Diamond Backed Watersnake

Nerodia

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Green Snake

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Coral Snake

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Superorder Archosauria • Includes

extinct

dinosaurs/pterosaurs and birds • 23 species of crocodiles, alligators, & caimans •

Largest

of the living reptiles • Amphibious

carnivores

• Live in tropics/subtropics 63

• Lizard-like body with

short

legs, clawed/webbed toes, massive

tail

• Flat head with nostrils at

tip

• Powerful

jaws

• Dorsal side

armored

with dermal plates

Dinosaurs

Dominate animals in Mesozoic Era

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• Extinct • Ichthyosaurs

Euryapsid

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Synapsids

• • Pelycosaurs

Dimetrodon

– Mammal like reptile 67

Order Crocodilia

• • • Crocodiles • Caimans • Alligators • Gavials

Elongated Four

heart skull chambered 68

Alligator 69

•

Elevated

eyes

Caiman

70

Gavial

71

Alligator Caiman Crocodile Gavial 72

The End

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