Do you know?

• Top/back of an animal? • dorsal • Front/belly of an animal? • ventral • Head end of an animal? • anterior • Tail end of an animal? • posterior • 8 levels of classification? • Domain • Kingdom • Phylum • Class • Order • Family • Genus • Species • Domain: Eukarya • Kingdom: Animalia • Phylum: Chordata • Class: Reptilia

Reptile Vocab

• Secondary palate - plate of bone that separates the nasal and oral cavities of mammals and some reptiles • Most reptiles do NOT have the secondary palate. This requires them to hold their breathe while swallowing. • Snakes and crocodilians have adapted other structures. • Autotomy - the self-amputation of an appendage • Defense mechanism in lizards • Median (parietal) eye - photoreceptor located middorsally on the head of reptiles • Covered with skin, normally can not form images. Used to detect light and dark and detect orientation of the sun. • Jacobson’s (vomeronasal) organs- olfactory receptor present in most reptiles. Blind- ending sacs that open through the secondary palate into the mouth cavity. Used to sample airborne chemicals.

• Pit organs - receptor of infrared radiation (heat) on the heads of some snakes (pit vipers). • Keratin - tough, water-resistant protein found in the epidermal layers of the skin of reptiles, birds, and mammals. • Plastron - the ventral portion of the shell of a turtle. Formed from bones of the pectoral girdle and dermal bone. • Carapace - the dorsal portion of the shell of a turtle. Formed from a fusion of vertebrae, ribs, and dermal bone. • Amniotic eggs - the egg of reptiles, bird and mammals. It has extraembryonic membranes that help prevent desiccation, store wastes, and promote gas exchange. These adaptations allowed vertebrates to invade terrestrial habitats.

Evolutionary Pressures

• What adaptations do reptiles show that allow them to live on land? • Chuckwalla • Burrowing • Aestivation - periods of inactivity • Sleep through summer and winter • Wedge themselves between rocks • scales Chapter 20

Reptiles: The First Amniotes • External Structure and Locomotion • Skin has no respiratory function • Skin is thick, dry and keratinized • Scales are modified for different functions • Periodically shed skin (ecdysis) • Chromatophores provide color • Cryptic coloration, mimicry, aposematic coloration, sex recognition Cryptic coloration Aposematic coloration Mimicry • Support and Movement • Skeleton very similar to amphibians • Skull is longer • Secondary palate present in some • Modified neck structure • Additional cervical vertebrae gives more freedom of movement to the head (twisting and nodding) • Modified ribs • Turtles - fused with shell • Snakes - aid in locomotion, inflate in defense • Limbs positioned closer to body • Changes movement • Nutrition and Digestion • Most are carnivores, but can eat many things • Turtles and crocodile’s tongues aid in swallowing • Some lizards have projectile tongues • Snake modifications • Jaw unhinges • Glottis (respiratory opening) is far forward in the mouth • Allows them to breathe while swallowing • Vipers have hollow fangs with venom • Some spit venom • 2 types of venom • Neurotoxin - attacks nervous system • Hemotoxin - breaks down blood cells

• Creepy! • Circulation, gas exchange, temperature regulation • 3 chambered heart • Breathe using lungs • Cold-blooded • Nervous and Sensory Functions • Brain larger than amphibians • Associated with increased sense of smell, reliance on vision and better coordination • Vision is dominant snese • Nictitating membrane present • Median (parietal) eye

• Jacobson’s organs • Pit organs • Magnetic detection • Present in sea turtles • Used to navigate the ocean • Excretion and osmoregulation • Kidneys adapted to conserve water (metanephric kidneys) • Cloaca excretes solid/powdery waste • Reproduction and development • Internal fertilization • Must occur in reproductive tract of female • Must occur before protective egg membranes are formed • Amniotic egg • Pores in shell allow gas exchange • Egg provides nutrition for embryo

• Parthenogenesis • Does not require egg to be fertilized • Occurs in some lizards • Males have never been found • Behavior • Males often seek out females • Courtship • Color changes • Head bobbing • tail waving • Pheromones • Vocalizations in crocodilians only • Egg laying • Eggs are usually abandoned • Crocodilians usually guard nests • Turtles bury eggs • In some species, egg temperature determines sex of offspring Popular Reptile Pets

• Bearded Dragon Worst Reptilian Pets

• Burmese Python Anapsid Reptiles

• Subclass Anapsida • Order Testudines (Chelonia) • Turtles • Appear in fossil record 200 million years ago • Shell • Carapace - dorsal covering • Plastron - ventral covering • 2 layers • Outer - keratin • Inner - bone

• Breathing • Limited room for lung expansion • Expand and contract diaphragm to breathe • Nervous system • Small brain • Poor hearing • Good sense of smell and vision

• Reproduction • Oviparous • Internal fertilization • Eggs are buried • Hatchling gender • Some turtle families - nest temperature determines gender • Low temp - males • High temp - females Diapsid Reptiles

• Subclass Diapsida • Order Squamata • Lizards, snakes, worm lizards • 95% of all reptiles • Snakes • Elongated body • Rearrangement of internal organs • Specializations for eating large prey • Kinetic skull - mobile jaws • Lizards • Geckos • Small, agile • Nocturnal • Adhesive pads on toes • Iguanids • Brightly colored • Throat fans, crests, frills • Skinks • Elongated bodies • Reduced limbs • Chamelions • Arboreal lizards • Specialized tongue • Lizard characteristics • Moveable eyelids • Good daytime eyesight • External ear • Vocalization • Geckos are territorial • Other lizards are defensive • Excretion • Semi-solid urine • Conserves water • Worm Lizards • Burrowing • No external limbs • Move forward and backward • Eyes are ears hidden by skin • Snakes • skeleton • Limbless, no pelvic girdles • Short, wide vertebrae • Ribs provide resistance to lateral stress • Highly kinetic skull • 2 halves of lower jaw connected only by muscle

• Senses • Permanent transparent eyelid • Jacobson’s organs

• Venomous snakes • Neurotoxic - affects the nerves • Hemorrhagin - breaks down red blood vessels

• Order Sphenodontida • 2 living species • Found in New Zealand • Tuatara • Lizardlike • Live over 75 years • Well developed median eye • Order Crocodylia • Mostly unchanged for 200 million years • 3 families • Crocodiles • Alligators • Caimans • Elongated, well-reinforced skull • Complete secondary palate • 4 chambered heart • Oviparous • Lay 20 - 50 eggs • Care for young • Crocs vs. alligators • Crocodiles • Narrow snout • Lower teeth visible when mouth closed • Alligators • Wider snout • No bottom teeth visible when mouth closed • Gavials • Very narrow snout