Class Reptilia “To Creep”

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

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

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

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

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

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

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

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)

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

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 – 14-20 eggs Sea Turtles – 400 eggs

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)

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

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)

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

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

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

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

Natural History Class Reptilia Various life spans Tortoise – 150 years Crocodiles – 20-40 years Snakes – 10-20 years

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

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

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