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Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Dec 14, 2015

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Page 1: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Reptiles

Page 2: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.
Page 3: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish

Page 4: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

310 million years ago… reptiles were the first vertebrates to make the complete transition to life on land

• limited competition for the insects and plants that could be used as food on the land

• an increase in competition for food and space among all the life-forms in aquatic environments

Page 5: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Adaptations to Land

Page 6: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Waterproof Skin• dry body covering of horny

scales or plates– develops as surface cells

fill w/ keratin- same stuff as bird

feathers and fingernails– prevent water loss (lipids

and proteins)– protect from wear and tear

associated w/ living in rugged terrestrial environments, keeps out germs

– unlike amphibians who can’t be far from water or they’ll dry out

Page 7: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

External Structural Adaptations (for land)

• some limbs have toes w/ claws – permit to climb,

dig, and move in various terrains

• others have toes modified into suctions cups – aid in climbing

• absence of limbs – snakes use scaly

skin and highly developed skeletal and muscular systems

Page 8: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

TURTLE EXTERNAL ANATOMY

Page 9: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Nictitating membraneTympanic membraneExternal naresOnly reptiles with NO TEETH

Page 10: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

NAME THE MEMBRANES

Red arrow = ?

Function= ?

Green arrow = ?

Function =?

Nictitating membrane

Protect eyes; “Swim goggles”

Tympanic membrane

eardrum

Page 11: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Limbs at right angles to body

Page 12: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Location of

Pelvic and Pectoral girdles allow turtle to pull limbs into shell

http://www.biosci.ohio-state.edu/~eeob/anatomy/eeob512/miscellaneous/turtleskeleton.jpg

Page 13: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Claws on feet

Page 14: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

SHELL IS LIVING PART OF BODY

Expanded ribs form shellCan regenerate damaged scutesGrowth rings tell age

Page 15: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

The small segments on a turtle’s shell are called ______________scutes

This part of the shell that covers theDorsal surface is the _______________

carapace

Page 16: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

This part of the shell on the ventral surface is the _______________

plastron

Bridge

This side part that connects the upper and lower shells is the _________________

Page 17: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

MALE PLASTRON slightly CONCAVE to fit on top of female

CURVE OF PLASTRON

FEMALE PLASTRON slightly CONVEXto make more room for eggs

Page 18: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

This part of the shell is the ________bridge

It connects the ___________ and ________________

plastron carapace

Image by Riedell/Vanderwal©2005

Page 19: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

TURTLE INTERNAL ANATOMY

Page 20: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

TURTLE LATIN meaning

KINGDOM _____________

PHYLUM ____________________________

SUBPHYLUM ___________________________

CLASS _______________________________

ORDER _____________________________

ANIMALIA

CHORDATA

VERTEBRATA “backbone”

REPTILIA “to creep or crawl”

CHELONIA “tortoise”

Page 21: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

NERVOUS

• COMPLEX BRAIN

• DORSAL SPINAL CORD

(Spine is fused to shell)

• Cranium (skull bone)

• Nerves connecting to spinal cord and brain

Page 22: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Nervous Cont.

• Cerebellum–Controls balance & motor

coordination

• Medulla oblongata• Controls involuntary organs

• Cerebrum• Controls higher thinking and learning

Page 23: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Nervous Cont.• Tympanic membrane

– Eardrum• Bone connecting eardrum to inner ear: columella

• Olfactory lobe– Smell

• Optic lobes– Processes info about vision

• Jacobson’s organ– Sense organ for smell in roof of

mouth of snakes & lizards

Page 24: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.
Page 25: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

TURTLE BRAIN

BIGGER CEREBRUM than same sized amphibian

Image modified from: http://theturtlepages.crosswinds.net/anatomy/reprodexc.html

Page 26: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

ENDOCRINEGlands that make

hormones that control other body organs

THYROID: located above heart Makes hormones that control heart rate, blood pressure; cell development and growth

PANCREAS controls

blood sugar levels

Page 27: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Respiration

• Well developed lungs (not gills)– tissues

involved in gas exchange area located inside body- kept moist

in even driest environments

Page 28: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

PHARYNX

GULLET

GLOTTIS

(Opening to lungs )

INTERNAL NARES (connects to External

nares “nostrils”)

Page 29: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Tell one thing you could look for to tell which of these tubes is the trachea and which is the esophagus?

Look for the cartilage rings. That’s the trachea,air tube that connects the larynx to the lungs.

Page 30: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

BRONCHI

• Two tubes that connect the lungs with the trachea

• Carry air.

Page 31: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

This is the _____g_lungg

Image by Riedell/Vanderwal©2005

Its function is Gas exchange

• Fills lungs by expanding rib cage.

• Pressure reduced within thorax draws in air.

Page 32: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

LUNGS HAVE ALVEOLI

TURTLE LUNGIncrease surface area for more gas

exchangeImages modified from: http://www.stclement.pvt.k12.il.us/studentWeb/science98/GarrittPatM/alveoli.gif

Page 33: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Circulation• like amphibians have

double circulation• most have 3 chambered

heart• partial division of ventricle

separates oxygen-poor blood flowing from the body from the oxygen-rich blood returning from the lungs

• alligators and crocodiles have 4 chambered hearts – separation of

oxygenated and deoxygenated blood

Page 34: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

TURTLE HEART

3 CHAMBERS

2 atria; 1 ventricle

Sinus Venosus & Conus Arteriosus are smaller

PARTIAL SEPTUM:

begins to divide ventricle into two sides

Image from: BIODIDAC

Page 35: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Circulation• Right atrium: Receives blood

from sinus venosus • carries only LOW oxygen blood

• Left atrium: Receives blood from lungs

• carries only HIGH oxygen blood

• Sinus venosus: Receives deoxygenated blood from body (smaller)

• Conus arteriosus:sends oxygenated blood to organs and deoxygenated blood to lungs. (smaller)

• Ventricle: pumps blood out of the heart

• Carries both high and low oxygen blood

#1 #2

#3

Page 36: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Circulation

• Veins carry deoxygenated blood to the heart. • Arteries carry away oxygenated blood from the heart.

– Pulmonary artery can be constricted so blood bypasses lungs to warm body quickly!

• Capillaries carry oxygenated blood that will diffuse into organs.

Page 37: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Single Loop: Fish Double Loop: Amphibians & Reptiles

Page 38: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Sinus venosus

RIGHTAtrium

Ventricle Conus arteriosus

Lungs

Bodyorgans

LEFTAtrium

FROG/TURTLE CIRCULATION

Page 39: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

SPLEENMake, store, recycle RBC’s

Page 40: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Digestive System

Image from:http://theturtlepages.crosswinds.net/anatomy/index.html

Vent

Page 41: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Image from: http://www.spc.cc.tx.us/biology/jmckinney/Studyimages/turtle/turtledissectlist.html

Page 42: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

This tube is the_______________esophagus

It carries __________to the ___________

food stomach

Page 43: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

STOMACH

Add ACID; Start DIGESTION; Grind & mash food

Page 44: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

SMALL INTESTINE Duodenum Ileum

LARGE INTESTINE(Also called COLON)

Page 45: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Name this part

of the tube

duodenum

Give a functionAdd trypsin,bileFinish digestionAbsorb nutrients

Image by Riedell/Vanderwal©2005

Page 46: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Pink arrow = ?

____________

Function = ?

______________

Ileum (SI)

Finish digestionAbsorb nutrients

Image by Riedell/Vanderwal©2005

Page 47: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Red arrow = ?

____________

Give a function

Large intestine

Also called the COLON

Collect/concentrate digestive waste

Image by Riedell/Vanderwal©2005

Page 48: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

LIVER

Makes BILE

Stores GLYCOGEN

Stores VITAMINS

Processes TOXINS

including nitrogen waste for kidneys

Page 49: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

GALL BLADDER

Stores BILE

Page 50: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

PANCREASIn mesentery near first loop of small intestine

Makes TRYPSIN, INSULIN, GLUCAGON

Page 51: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Red arrow = ?

Name the body systems that empty here

cloaca

Excretory, digestive, reproductive

Image by Riedell/Vanderwal©2005

Page 52: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

MESENTERY

This membrane that holds the digestive organs in place

Page 53: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

This exit opening

is the __________

vent

Name the body systems that use this exit__________________Digestive, excretory, & reproductive

Page 54: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

WHAT SEX IS IT?

FEMALES: MALES: Short tail Longer tailVent closer Vent farther from body

Page 55: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

REPRODUCTIVE

MALE FEMALE

Images modified from:http://theturtlepages.crosswinds.net/anatomy/index.html

VentVent

Page 56: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

OVARY- • make eggs

OVIDUCT-• add shells• transport to

cloaca

Page 57: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Image from: BIODIDAC

EPIDIDYMIS –sperm mature here; add tails

TESTES –

make sperm

Page 58: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

INTERNAL FERTILIZATION

Increases chances of sperm and egg meeting

Image from: http://www.turtletimes.com/PhotoContest/2001PhotoContests/May2001/Geoemyda%20spengleri%20mating.jpg

Page 59: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

SEX is determined by TEMPERATURE of NEST

Image from:http://www.parcplace.org/documents/GeneralHerpInfo/learnabout2.htm

Page 60: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Types of Reproduction

Page 61: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Ways offspring enter world

OVIPARITY- Reproductive tract encloses egg in a protective shell

Eggs deposited outside body to hatchNourishment comes from egg

EX: Most reptiles,birds & a few mammals (monotremes)

Page 62: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Ways offspring enter world

VIVIPARITY-

No shell around egg

Eggs retained in body

Nourished by mother through placenta

Offspring are born alive

Ex: Mammals & some reptiles

Page 63: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

OVOVIVIPARITY-

Egg surrounded by protective shellbut kept in body until just before hatching or can hatch inside female

Nourishment comes from egg not mother

Ex: Some reptiles (snakes)

Ways offspring enter world

Page 64: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

OVI

PARITY

OVOVIVI

PARITY

VIVI

PARITY

SHELL?

NO SHELL?

Embryo grows?

Food comes

From?

Seen in?

SHELL

OUTSIDE

EGG

Birds,Reptiles,Few mammals

NO SHELL

INSIDE

MOTHER

Mammals,few reptiles

SHELL

INSIDE

EGG

Reptiles

Page 65: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Amniote Egg

• The allantois stores the nitrogenous wastes produced by the embryo until the egg hatches

• an egg with a protective membrane and a porous shell enclosing the developing embryo.

-It forms a “nursery” to protect the embryo

- The egg derives its name from the amnion, the thin membrane enclosing the salty fluid in which the embryo floats.

• They yolk sac encloses the yolk, a protein rich food supply for the developing embryo

Page 66: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

• The chorion lines the outer shell and thus encloses the embryo and all the other membranes. It regulates the exchange of oxygen and carbon dioxide between the egg and the outside environment.

• The entire amniote egg is surrounded by a leathery shell that may be hard in some species because of the presence of calcium carbonate.

-The egg is water proof, however it allows gases to flow between the environment and the chorion.

• The male places the sperm inside the female before the shell is formed. This is called internal fertilization, makes water transport of sperm unnecessary.

Page 67: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

DIRECT DEVELOPMENT

Image from: http://www.neuroscientist.com/animimag/turtles.htm

Page 68: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Excretion

• conserve water by excreting nitrogenous wastes in dry or pasty form as crystals of uric acid

Page 69: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Blue arrow = ?

kidney

Function ?

Excrete nitrogen waste (make urine) osmoregulation

Image by Riedell/Vanderwal©2005

Page 70: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Give a function

Name the form of nitrogen waste excreted by reptiles

The red arrow = ? ______________Urinary bladder

Store urine

Uric acid

Image by Riedell/Vanderwal©2005

Page 71: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Temperature Regulation

• metabolism rate controlled in part by body temperature

• Ectothermic (cold-blooded) – body temp controlled by environment

• not endothermic (warm-blooded)

• regulate their temp by behavior

– bask in sun to speed up metabolism

– hide in shade to prevent overheating

Page 72: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

ECTOTHERMICADVANTAGES: Slow metabolism means you can survive on 1/10 the food as a same size endotherm

DISADVANTAGES:• Can’t to live in extremely cold places (NO reptiles in Arctic)

• Can’t keep up max activity level for long

Page 73: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

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.

- Fossils indicate that these four-legged, sprawling vertebrates resembled small lizards and had teeth used for eating insects

-The abundance of insects at the time may have been one reason the cotylosaurs flourished.

• during the Permian period these reptiles began to adapt to other available environments, giving rise to new forms of reptiles.

- These groups included flying reptiles called pterosaurs

• - Two groups of marine reptiles: the ichthyosaurs and plesiosaurs

• - And the thecodonts

Page 74: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

• The dominant land reptiles came from the thecodonts.

- The small lizard-like carnivores, many of which walked on their hind legs.

• The thecodonts were the first archosaurs ( “ruling reptiles”), a group that later included the early crocodiles, the dinosaurs, and the reptiles that evolved into birds.

• The Mesozoic era is known as the Age of Reptiles.

- During this time reptiles , esp. the dinosaurs, dominated all other forms of life.

- Dinosaur means “terrible lizard” however many of the dinosaurs were small.

• Yet the incredible size of some dinosaurs distinguish the group from all other forms of life.

-One of the largest dinosaurs was the brachiosaurus, 77,00 kg.

• It was as long as a tennis court, as tall as a four-story building, and heavier than elephants.

Page 75: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

• Over 300 genera of dinosaurs have been identified around the world. -They were adapted to a wide range of environments.• Brachiosaurus and such related dinosaurs as Diplodocus and

Apatosaurus were herbivores, plant eaters. - They probably used their long necks to reach the top of trees.• Tyrannosaurus and other carnivores, or meat eaters, walked on their

hind legs and used sharp teeth and huge claws to rip apart prey.• The scientist who studies dinosaurs are known as Paleontologists.

Page 76: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Modern Reptiles• Reptiles are classified into 16 orders, 12 that are extinct. - 4 surviving-6, 000 species• Reptiles occur worldwide except in coldest regions - Human intervention-major impact• 4 living orders of Class Reptilia: - 1. Rhynchocephalia, - 2. Chelonia, - 3. Crocodilia, - 4. Squamata

Page 77: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Rhynochocephalia• Only living species-

Sphenodon punctatus- the tuatara

-  Inhibit islands of coast of New Zealand

- Resembles a large lizard about 60 cm long

- Has an inconspicuous third eye on top of its head- parietal eye- functions as a thermostat- protects from overheating

- Active at low temperatures and feed at night on insects, worms and small animals

Page 78: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Chelonia• Order consists of about 265

species of turtles and tortoises - Tortoise are terrestrial

Chelonia (Galapagos tortoises) - Turtles- chelonians that live

in water - Body covered by a shell

made of hard plates- 2 parts- a carapace and plastron

- Shape is modified for variety of ecological demands

- retract heads, swimming - Forelimbs of a marine

turtle have evolved into flippers and freshwater turtles have webbed toes

- Migratory behavior of sea and river turtles

-return to land to lay eggs

Page 79: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Crocodilia• Order composed of 20 species

of large lizard-shaped reptiles- crocodiles, alligators, caimans and gavials 

- Descendants of archosaurs

• Crocodilians live in or near water in tropical/ subtropical regions of the world

• - Crocodiles- nocturnal animals; Africa, Asia and Americas

• -  Alligators - China and southern U.S.

- Caimans- Central America- some in Florida

- Gavials- eat fish; long and slender snout- live only in Burma and India

Page 80: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

• Carnivorous- hunt by stealth- features adapted for this behavior  - Eyes on head, nostrils on top of snout

-see and breathe while in water

- Valve to prevent water from entering air passage

- Parental care- both parents care for young by carrying in jaws until development

Page 81: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Squamata• Order consists of 5,640 species

of lizards and snakes - Loosely jointed upper jaw and

paired reproductive organs in males

- Structurally diverse• Lizards- presence of limbs• - Common lizards- iguanas,

chameleons, skinks and geckos  -  Live everywhere except

Antarctic - Special adaptations- agility

and camouflage - 2 species are venomous- Gila

monster (SW U.S.) and beaded lizard (western Mexico)

- Most prey on insects or small animals

Page 82: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

- Blend with background - chameleons- remain

inconspicuous and fend off enemies - Horned lizards- spiked armor,

when disturbed they inflate themselves, gape, hiss and squirt blood from eyes

- Skinks and geckos- lose their tails and regenerate- autotomy- escape from predators

- Most lizards are small- .3m in length; iguanas- 1m in length

- Largest lizards- monitors- Komodo dragon (Indonesia) 3m

(9.8 ft) in length, 140 kg (308.6 lbs) - Thought to be related to

snakes - have a forked tongue for sense

organs - Consume prey whole and use

tail as defense weapon

Page 83: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Adaptations of Snakes

Page 84: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Snakes probably evolved from lizards that lived above ground found during

the Cretaceous period.

Page 85: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Movement• A snake has a backbone

of 100 to 400 vertebrae, each of which has a pair of ribs attached.

- Providing the framework for thousands of muscles

• The interaction of bones, muscles, and skin enables asnake to move in one of three basic ways:

1. Lateral undulation 2. rectilinear

movement 3. side winding.

Page 86: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Movement cont.• Most commonly move by

lateral undulation. - moving forward in an S

shaped path.• In rectilinear movement, the

snake applies muscular force on its belly, not its sides.

- Scutes are scales on its belly that catch on bark orother rough surfaces (like a caterpillar).

• Some desert-dwellers snakes progress by side-winding.

Page 87: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Feeding

• Snakes eat animals, but lack structural adaptations common to other carnivores.

• Snakes do not see or hear well, and have no limbs, and their teeth and small mouth cannot rip and grind flesh.

Page 88: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Locating Prey

• Snakes evolved a sense of smell which they use to locate their prey.

- By flicking its forked tongue , a snake gathers chemicals from the environment.

• The tongue transfers these chemicals to two pits in the roof of the mouth called the Jacobsons organ where the nerves are highly sensitive to the chemicals.

Page 89: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Locating Prey Cont.• Some snakes inject their

prey with Toxic venom• most bite down their fangs

and inject the poison into their prey.

• Venom is chemically complex.

- The hemotoxins  are proteins that attack the circulator system, destroy red blood cells and disrupt the clotting power of blood.

- The neurotoxins work on the nervous system, by disrupting the nerve pathways which is dangerous to respiratory and heart functions.

Page 91: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Defense

• Natural selection resulted in modifications for defense.• Camouflage is beneficial for both seeking prey and

hiding from predators. - many snakes are green and blend with foliage - others are brown and hide against the bark of trees

Page 92: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Defense Cont.

• Some snakes defend themselves by signaling their presence.

• Some ward off danger by rapidly changing body shape- extending a hood like cobras

• Some hiss• Others make

mechanical noises - such as the rattle of

the rattlesnake.

Page 93: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Reproduction

• Most male snakes rely on the scent of female snakes of heir own species.

• 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.

• Fertilization is internal.

Page 94: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.

Reproduction cont.• Most snakes are oviparous - female lays eggs that

hatch outside her body. - To break out a hatchling

uses a special tooth which is lost soon after.

• Other snakes are ovoviviparous

- the female carries the eggs in her body throughout development

• the young are born live. - All newborns must fend

for themselves, relying on their many specialized adaptations for survival on land.

Page 95: Reptiles. Scientists believe other land vertebrates evolved from BONY LOBE-FINNED fish.