1. Reptiles

2. Key features of Reptiles
Strong, bony skeletons and toes with claws
Two pairs of limbs, except snakes
Legs positioned vertically for support of body and movement on land

3. External Structural Adaptations for Land
Claws-aid in climbing, digging and movement in various terrains
Toes modified into suctions cups aid in climbing
Absence of limbs
Snakes use scaly skin and highly developed skeletal and muscular systems to move

4. Ectothermic Metabolism
Regulate their temperature by basking in the sun or seeking shade
Become sluggish in very cold temperatures
Intolerance to cold limits their geographic range

5. Temperature Regulation
Regulate their temp by behavior
Bask in sun to speed up metabolism
Hide in shade to prevent overheating

6. Reptiles Continued Dry, scaly skin, almost watertight
Amniotic eggs, almost watertight
Contains a water and food supply
Respiration through well developed lungs
Grape shaped chamber called alveoli
Alveoli increase the respiratory surface area for gas exchange
Strong muscles in rib cage help to move air in and out

7. Respiration Well developed lungs
Tissues involved in gas exchange are located inside body
Kept moist in even in the driest environments

8. Heart Ventricle of heart partly divided by a septum
Still incomplete separation of oxygen-rich and oxygen-poor blood
Crocodiles and alligators
have a ventricle that is totally separated into two pumping chambers

9. Double loop circulation

10. Reproduction Internal fertilization
Many reptiles are oviparous-young hatch from eggs
Some lizards and snakes are ovoviviparous-female retains eggs in her body until shortly
before hatching or hatching
may occur inside her body

11. Excretion
Conserve water by excreting nitrogenous wastes in dry or pasty form as crystals of uric acid

12. 1st Orders of Reptiles Squamata
Snakes and lizards
lower jaw is loosely connected to skull allowing mouth to open wide to accommodate large prey
Lizards can regenerate tail, but will not have vertebrae
Molting occurs in both

13. Squamata Order consists of 5,640 species of lizards and snakes
Loosely jointed upper jaw and paired reproductive organs in males
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)

14. Squamata Continued
Blend with background chameleons- remain inconspicuous
Horned lizards- spiked armor,when disturbed they inflate,hiss and squirt blood from eyes
Skinks and geckos- lose their tails and regenerate-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)

15. Adaptations of Snakes

16. Movement
A snake has a backbone of 100 to 400 vertebrae, with a pair of ribs attached
Provides the framework for thousands of muscles
Interaction of bones, muscles, and skin enables a snake to move various ways:
Example:
side winding

17. Feeding Snakes eat animals, but lack
structural adaptations common to other carnivores
Snakes do not see or hear well, have no limbs, and teeth and small mouth cannot rip and grind flesh

18. Locating Prey
Snakes evolved a sense of smell which they use to locate their prey
Flicks its forked tongue to gather chemicals from the environment
Transfers chemicals to two pits in the roof of the mouth-Jacobsons organ where nerves are highly sensitive to the chemicals
Some snakes inject toxic venom by biting with fangs and injecting
Hemotoxins-attack the circulator system-disrupt the clotting of blood.
Neurotoxins-disrupting the nerve pathways-dangerous to respiratory and heart functions.

19. 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

20. Reproduction Continued
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
Female carries the eggs in her body throughout development
Young are born live
All newborns must fend for themselves, relying on their many specialized adaptations for survival on land

21. 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

22. 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

23. Defense Continued 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.

24. 2nd Order of Reptiles Chelonia
Turtles and tortoises
Hard bony shell-dorsal
is carapace and
ventral is plastron
Lack teeth, but have beaks
Many herbivores but some are carnivores

25. Chelonia Order consists of about 265 species of turtles and tortoises
Tortoise are terrestrial
Turtles live in water
Body covered by a shell made of hard plates- 2 parts- a carapace and plastron
Retractable head
Forelimbs of a marine turtle have evolved into flippers and freshwater turtles have webbed toes
Migratory behavior of sea and river turtles
Returns to land to lay eggs

26. 3rd Order of Reptiles Crocodilia
Crocodiles and alligators
Most closely related
to dinosaurs
Aggressive carnivores
Care for their young after hatching

27. Crocodilian
Order composed of 20 species of large lizard-shaped reptiles- crocodiles, alligators, caimans and gavials 
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

28. Carnivorous
Eyes on head, nostrils on top of snout
See and breathe while in water
Parental care- both parents care for young by carrying in jaws until development

29. 4th Order of Reptiles Rhynchocephalia
Tuataras
Two species native to New Zealand
Most active at low temperatures

30. Rhynochocephalia Only living species-New Zealand
Resembles a large lizard about 60 cm long
Parietal eye-functions as a thermostat-protects from overheating
Active at low temperatures, feed at night on insects, worms and small animals

31. 310 million years ago… reptiles were the first vertebrates to make the complete transition to life on land
An increase in competition for food and space among all the life-forms in aquatic environments
Limited competition for the insects and plants that could be used as food on the land

32. Adaptations to Land

33. Adaptations to Land
Amniotic Egg
Legs
Lungs
Scales or plates

34. Amniotic Egg
An egg with a protective membrane and a porous shell enclosing the developing embryo
Egg forms a “nursery” to protect the embryo
Egg derives its name from the amnion, the thin membrane enclosing the salty fluid in which the embryo floats
Yolk sac encloses the yolk, a protein rich food supply for the developing embryo
Allantois stores the nitrogenous wastes produced by the embryo until the egg hatches

35. The chorion regulates the exchange of oxygen and carbon dioxide between the egg and the outside environment
Amniote egg is surrounded by a leathery shell that may be hard in some species (Birds) because of the presence of calcium carbonate
The male places the sperm inside the female before the shell is formed. This is called internal fertilization, makes water transport of sperm unnecessary

36. 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.

37. The End