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

Adaptations to Land

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

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

TURTLE EXTERNAL ANATOMY

Nictitating membraneTympanic membraneExternal naresOnly reptiles with NO TEETH

NAME THE MEMBRANES

Red arrow = ?

Function= ?

Green arrow = ?

Function =?

Nictitating membrane

Protect eyes; “Swim goggles”

Tympanic membrane

eardrum

Limbs at right angles to body

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

Claws on feet

SHELL IS LIVING PART OF BODY

Expanded ribs form shellCan regenerate damaged scutesGrowth rings tell age

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

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

carapace

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 _________________

MALE PLASTRON slightly CONCAVE to fit on top of female

CURVE OF PLASTRON

FEMALE PLASTRON slightly CONVEXto make more room for eggs

This part of the shell is the ________bridge

It connects the ___________ and ________________

plastron carapace

Image by Riedell/Vanderwal©2005

TURTLE INTERNAL ANATOMY

TURTLE LATIN meaning

KINGDOM _____________

PHYLUM ____________________________

SUBPHYLUM ___________________________

CLASS _______________________________

ORDER _____________________________

ANIMALIA

CHORDATA

VERTEBRATA “backbone”

REPTILIA “to creep or crawl”

CHELONIA “tortoise”

NERVOUS

• COMPLEX BRAIN

• DORSAL SPINAL CORD

(Spine is fused to shell)

• Cranium (skull bone)

• Nerves connecting to spinal cord and brain

Nervous Cont.

• Cerebellum–Controls balance & motor

coordination

• Medulla oblongata• Controls involuntary organs

• Cerebrum• Controls higher thinking and learning

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

TURTLE BRAIN

BIGGER CEREBRUM than same sized amphibian

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

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

Respiration

• Well developed lungs (not gills)– tissues

involved in gas exchange area located inside body- kept moist

in even driest environments

PHARYNX

GULLET

GLOTTIS

(Opening to lungs )

INTERNAL NARES (connects to External

nares “nostrils”)

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.

BRONCHI

• Two tubes that connect the lungs with the trachea

• Carry air.

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.

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

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

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

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

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.

Single Loop: Fish Double Loop: Amphibians & Reptiles

Sinus venosus

RIGHTAtrium

Ventricle Conus arteriosus

Lungs

Bodyorgans

LEFTAtrium

FROG/TURTLE CIRCULATION

SPLEENMake, store, recycle RBC’s

Digestive System

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

Vent

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

This tube is the_______________esophagus

It carries __________to the ___________

food stomach

STOMACH

Add ACID; Start DIGESTION; Grind & mash food

SMALL INTESTINE Duodenum Ileum

LARGE INTESTINE(Also called COLON)

Name this part

of the tube

duodenum

Give a functionAdd trypsin,bileFinish digestionAbsorb nutrients

Image by Riedell/Vanderwal©2005

Pink arrow = ?

____________

Function = ?

______________

Ileum (SI)

Finish digestionAbsorb nutrients

Image by Riedell/Vanderwal©2005

Red arrow = ?

____________

Give a function

Large intestine

Also called the COLON

Collect/concentrate digestive waste

Image by Riedell/Vanderwal©2005

LIVER

Makes BILE

Stores GLYCOGEN

Stores VITAMINS

Processes TOXINS

including nitrogen waste for kidneys

GALL BLADDER

Stores BILE

PANCREASIn mesentery near first loop of small intestine

Makes TRYPSIN, INSULIN, GLUCAGON

Red arrow = ?

Name the body systems that empty here

cloaca

Excretory, digestive, reproductive

Image by Riedell/Vanderwal©2005

MESENTERY

This membrane that holds the digestive organs in place

This exit opening

is the __________

vent

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

WHAT SEX IS IT?

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

REPRODUCTIVE

MALE FEMALE

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

VentVent

OVARY- • make eggs

OVIDUCT-• add shells• transport to

cloaca

Image from: BIODIDAC

EPIDIDYMIS –sperm mature here; add tails

TESTES –

make sperm

INTERNAL FERTILIZATION

Increases chances of sperm and egg meeting

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

SEX is determined by TEMPERATURE of NEST

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

Types of Reproduction

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)

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

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

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

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

• 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.

DIRECT DEVELOPMENT

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

Excretion

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

Blue arrow = ?

kidney

Function ?

Excrete nitrogen waste (make urine) osmoregulation

Image by Riedell/Vanderwal©2005

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

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

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

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

• 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.

• 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.

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

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

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

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

• 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

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

- 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

Adaptations of Snakes

Snakes probably evolved from lizards that lived above ground found during

the Cretaceous period.

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.

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.

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.

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.

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.

Swallowing and Digesting Prey

• A snakes upper and lower jaws are hinged and move independently.

• when unhinged, the jaws stretch to allow the mouth to open extremely wide.

• While swallowing it whole the snake thrusts its windpipe into the throat, allowing the snake to breathe

- the process of can take several hours.

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

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.

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.

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.