1. Reptiles

2. Objectives:
Objective 1: Describe the characteristics of Modern Amphibians
Objective 2: Describe characteristics of the following orders: (Apoda, Urodela, Anura)
Objective 3: Explain the origins and evolutionary process of modern amphibians
Objective 4: Describe the characteristics of modern Reptiles
Objective 5: Describe characteristics of the following orders: (Squamata, Sphenodonta, Crocodilia, Testudines)
Objective 6: Explain the characteristics of respiration, feeding, and reproductive strategies for reptiles
Objective 7: Identify the amphibians and reptiles in Idaho and the families they are associated with
Objective 8: Student Presentation of Amphibians and Reptiles.

3. # of Species of Reptiles
Species Numbers by Higher Taxa:
Amphisbaenia (amphisbaenians) 165
Sauria (lizards) 4765
Serpentes (snakes) 2978
Testudines (turtles) 307
Crocodylia (crocodiles) 23
Rhynchocephalia (tuataras) 2
Reptiles total 8240

5. Characteristics of a Reptile
Vertebrate animals
Lungs
Scaly skin
Amniotic egg
Characteristics of a Reptile
Vertebrate animals
Lungs
Scaly skin
Amniotic egg

6. Characteristics of Reptiles – Adaptations to life on land
More efficient lungs and a better circulatory system were developed for life away from water
Scaly skin provided protection against the elements and desiccation
The amniotic egg protected against desiccation

7. Reptile Lungs- Another Adaptation to Life on Land
A more efficient respiratory system
Reptiles use two efficient lungs (except snakes – they only have one long one that fits their bodies)

8. Reptile Lungs
Respiration is no longer through the skin, but only through internally protected and moistened lungs.
They have a much greater surface area for the exchange of gases.
They are inflated and deflated by the expansion & contraction of the rib cage.

9. Scaly Skin An adaptation to life out of water Waterproof Dry, leathery
Protective scales
Must be molted

11. Amniotic Egg – Reptiles and Birds
Compared to the development of seeds in plant evolution
Reptile eggs have leather shell
Has several membranes
Contains yolk rich in nutrients for embryo
Mammals have comparable modified membranes

12. The Amniotic Egg – adaptation to life on land
Amphibians were not able to move away from the water because their eggs would desiccate
Reptiles eggs prevent desiccation

13. Reptile Legs Short tetrapods for walking
Positioning of the legs more directly under the animal. This position provided more support than the splayed arrangement of the Amphibian legs.

14. Paired Limbs
The paired limbs usually have five toes and are variously adapted for:
Swimming
Running
Climbing
(Absent altogether in the snakes)

15. Evolution of Reptiles
TRANSITION FOSSILS show that there was a slow and steady evolution from amphibians to reptiles.

17. Age of the Large Reptiles
Approximately 195 million years ago, the mammal-like reptiles that populated the world disappeared and were replaced by the dinosaurs

18. Mass Extinction – 65mya
Scientists not sure why the dinosaurs disappeared
Possibly the world was hit by a meteor
Only relatively small reptiles were left behind

19. Reptile Feeding Ex. 1: Iguana
Herbivores – tear plants using teeth and jaws
Have long digestive systems

20. Carnivores
Snakes – have extendible jaws to swallow their prey hole.

21. Carnivores Some snakes have a diet of eggs exclusively.
They swallow the egg whole, pierce the shell with a specialized section of the vertebrate, suck out the insides and spit out the shell!

22. Carnivores
The king cobra eats other snakes

23. Carnivores
Monitor lizard – kills prey with sharp teeth and powerful jaws

24. Carnivores
Chameleons – have long sticky tongue that they flip out to catch flying insects .

25. Reptilian Respiratory System
Reptilian lungs are better developed than amphibians
Muscular ribs help them expand the chest cavity as we do to draw in the air
Nostrils allow them to bring in air while their mouth is closed
Snakes only have one long, lung that fits in their bodies.
Snakes also have a tube that projects out of the mouth when the snake is swallowing so that it can breathe and swallow at the same time

26. Breathing Tube

27. Internal Transport Double-loop system
Most reptiles have a 3 ½ chambered heart (ventricle has a partial septum)
Crocodiles and Alligators have a 4 chambered heart like ours.

29. Reptiles need a more efficient system for delivering oxygen since they have dry skin.

30. Excretion Kidneys produce urine in the form of uric acid
Uric acid crystallizes when concentrated, and is eliminated as a white paste (like birds)
Urine is either passed out directly through the cloaca, or stored in the urinary bladder where water is further reabsorbed

31. Nervous Systems Frog Brain Alligator Brain
Larger cerebrum/ cerebellum than the amphibians
Daytime reptiles have good color vision: turtles can see color better than humans

32. Excellent Sense of Smell - Snakes
Have pair of nostrils
Also have special organs (vomeronasal organs) on roof of mouth
Tongue picks up chemicals and brings them to the vomeronasal organs to “taste” the air

33. Hearing
Most lizards have simple ears like an amphibian: external tympanum, single bone to transfer sound to inner ear . (we have an internal tympanum and 3 bones)
Snakes have no ears and are deaf – they “hear” the vibrations from the ground

34. Hearing - tortoises
Tortoises do not have a tympanum, but have a sound-conducting patch of skin on their head.
A “Red Ear Slider” turtle

36. Heat Sensors
Pit vipers are able to detect heat, to obtain a temperature image of their environment
Normal view Infrared view Combined view

37. Jacobson’s Organ

38. Pit vipers

39. Movement
Muscle and skeletal systems are more advanced than amphibians

40. Snakes - movement Snakes press their ventral scales against the ground
Muscles around the ribs expand and contract in waves causing the s-shaped movement

41. Gecko – suction cup toes
Geckos have special flaps of skin on its toes – creating very sticky appendages

42. Reptile Reproduction Most have internal fertilization
Penis delivers sperm into cloaca of female

43. Reptile Reproduction Internal fertilization
Male inserts penis into female’s cloaca
Female’s body coats the embryos in protective shell, with membranes and yolk sac

44. Reptile Reproduction Most reptiles are oviparous
Some provide minimal care

46. Amniotic Egg

47. Amniotic Egg Structures & Functions
Chorion provides a special hard covering that is permeable to respiratory gases (O2 and CO2) while being impermeable to water vapor.
Allantois is a storage reservoir for metabolic waste products such as nitrogenous compounds.
Amnion is a fluid filled sac that acts as a cushion for the embryo and also prevents desiccation.
Yolk sac contains food for the embryo, thus eliminating the need for a larval stage.

48. The temperature inside the nest of several crocodilian species decides the sex of the young. ~50-80 eggs
If the nest temperature is 30ºC, females will hatch from all the eggs
If the temperature is above 34ºC, all will be males.
If the temperature is in between, there will be young of both sexes.

49. Orders to know: Objective 5
Order Squamata: Snakes, Lizards, and amphisbaenians. Skin of horny epidermal scales or plates, which is shed; quadrate movable; skull kinetic (except amphisbaeinians); vertebrae usually concave in front; paired copulatory organs. There are three suborders Lacertilia (lizards), Amphisbaenia (worm lizards), and Serpentes (snakes).
Order Sphenodonta: Tuataras. Primitive diapsid skull; vertebrae biconcave; quadrate immovable; parietal eye present; two extant species in Spenodon.
Order Crocodilia: Crocodiles and Alligators. Skull elongate and massive; nares terminal; secondary palate present; four-chambered heart; vertebrate usually concave in front; forelimbs usually of five digits; hind limbs of four digits; quadrate immovable; advanced social behavior; 23 species. Crocodiles and alligators can be distinguished on the basis of head morphology. Crocodiles have a relatively narrow snout and when their mouths are closed, the fourth lower jaw tooth is visible. Alligators generally have a broader snout and their fourth lower jaw tooth is hidden by fitting into a notch in the upper jaw.
Order Testudines: Turtles; Body in a bony case of dorsal carapace and ventral plastron; jaws with keratinized beaks instead of teeth; vertebrae and ribs fused to overlying carapace; tongue not extensible; neck usually retractable; approximately 300 species.

50. Tuataras Resembles small version of reptiles from the dinosaur age
Only found on small islands off N. Zealand
Has pineal gland on top of skull detects light – actually determines changes in length of day

51. Lizards – chameleons

52. Lizards – Gila Monsters - venomous

53. Hatchling Komodo Dragon

54. Monitor Lizards – may be like dinosaurs were.
Largest is the Komodo dragon

56. Family Amphisbaenidae (Worm Lizards)
Size: The total body length ranges from 10 cm to about 70 cm.
Distribution: Mostly Africa & South America with a few species in Europe and North America.
Habitat: Soil.
Reproduction: usually oviparous, but some are live-bearing

57. Ectothermy – “heat from outside”
Usually have relatively low resting metabolic rates
Therfore, they do not generate much body heat
Body temp. is actually higher than the surroundings
These animals remain active for short periods of time, then have rests in between activity

58. Endothermy – “heat from inside”
These animals have relatively high metabolic rates
They use this heat to keep their bodies warm
Usually have a lower internal temp. than the surroundings
Endotherms can remain active for longer periods of time
These animals have greater energy needs – need to eat more food than ectoderms

59. Snake Anatomy

60. Turtle Anatomy

61. Turtle Shell Anatomy

63. Turtle Shell Anatomy

64. Fusion of ribs, vertebrae, & carapace