1. Class Reptilia
“To Creep”

2. Class Reptilia Herpetology – the study of reptiles 8,000+ species
Evolved from amphibians
1st land animals

3. Major orders Squamata -- reptiles with scales; lizards, snakes
Chelonia – Turtles, tortoise
Crocodilia – Alligators, crocodile, caiman

4. Common Characteristics
Thick, dry waterproof skin, many with dry scales (terrestrial) – molt
Moveable joints – rapid movement
Claws to dig, climb, run
Ectothermic – cold blooded
Everywhere except Antarctica
Lungs

5. External Structure Generally tetrapods
Snakes – limbless, vestigial limbs
Nictitating membrane – eye protection
Tough, leathery skin
Cornified dermal plates
Keratin infused skin cells
Musk glands –
Produce scent – courtship, communication

6. Skeletal Axial – Cranium, vertebra, ribs (thoracic, abdominal, caudal)
Appendicular – Pectoral and pelvic girdle

7. Muscular Segmented muscles Striated – movement & locomotion
Smooth – involuntary – reflex
Cardiac – heart

8. Digestive Complete digestive Mouth
Teeth (grasping fangs, ripping, shredding)
Esophagus
Stomach
2 lobed liver
Pyloric valve
Small intestine
Pancreas
Large intestine
Rectum
Anus
Cloaca

9. Circulatory Closed system 4 chambered heart
2 auricles, 2 ventricles
Arteries – carry blood away to lungs
Dorsal artery & aorta – distribute blood
Capillaries – tie arteries and veins
Veins – return blood to…
Kidney – filters blood
Hepatic vein … anterior vena cava … sinus venosus (to heart)

10. Nervous System Brain divisions Olfactory – smell – nostrils
Cerebral – thought process
Optic lobe – sight
Cerebellum – coordination, equilibrium
Medulla oblongota – breathing, digestion, circulatory function
Spinal cord

11. Reproductive Most species are oviparous, some are ovoviviparous
Internal fertilization
Amniotic eggs – shell for protection, development
Range of eggs per laying
Gecko – 5-11 eggs
Pond Turtle – 10 eggs
Alligator – eggs
Sea Turtles – 400 eggs

12. Class Reptilia – Natural History
Natural history – the scientific study of plants and animals in their natural environments
Moderate climates – not too hot, not too cold; equatorial
Aestivation – hot and dry
Nocturnal – night activities
Diurnal – active 2x day (dusk/dawn)

13. Natural History – Turtles & Tortoises (Order Chelonia)
260 species
Bony shell
Carapace – dorsal portion of shell
Plastron – ventral portion of shell
No teeth – keratinized beak
Turtles – live in or near water, webbed feet, claws or nails, less domed shell
Tortoise – live on land, stumpy legs, high domed shell

14. Natural History – Snakes (Order Squamata)
2,300 species (300 venomous)
No appendages (up to 200 vertebrae)
Belly scutes – friction grasping plates for locomotion
No eyelids
No external ears
Jacobson’s Organ – forked tongue – smell and taste
Moveable upper jaw
Each jaw moves independently (quadrate bone)

15. Natural History – Snakes (Order Squamata) cont…
Forward glottis placement for breathing
Fangs -- collapsible
Venom gland
Venom can affect:
Nervous system – neurotoxin
Blood & muscle – hemotoxin
Constrictor – squeeze & suffocate
Some have pit organs (pit vipers) to detect heat

16. Natural History – Lizards (Order Squamata)
3,300 species
Tetrapods
United jaws
Moveable eyelids
External ears
Claws on each foot
Vary in length – few centimeters to 3 meters

17. Natural History – Crocodiles (Order Crocodilia)
17 living species
Long, slender snouts
Very aggressive
Thrashing motion to tear apart prey

18. Natural History – Alligators (Order Crocodilia)
Only 3 different species (only US & China)
Broad/wide snout
Less aggressive
Have existed for 170 million years

19. Natural History Class Reptilia
Various life spans
Tortoise – 150 years
Crocodiles – years
Snakes – years

20. Natural History Class Reptilia
Venomous reptiles
Gila monster – chew or shred skin – neurotoxin
Pit Viper – use heat pits – hemotoxin
Coral snake – small fangs – strike and hold – neurotoxin
Komodo dragon – largest lizard – flesh eating bacterial saliva

21. Natural History Class Reptilia
Other notable (but not venomous), deadly reptiles…
Reticulated Python – constrictors – 20+ feet
Crocodile – 22 feet & 2,000 pounds

22. Natural History Class Reptilia
King snake – looks very similar to a coral snake, but is not venomous
Eats other deadly snakes
Which is which?