Chapter 17D 1

Class Reptilia Characteristics 1. Skin Note: What is Keratin? Note: Why the need to keep heat in? Cool, dry, leathery. Scales composed of keratin. Keratin is a fibrous protein that is waterproof and durable. Skin has to be shed. Keeps the heat in. They are mostly Ectothermic! Reptiles have a skin that is composed of keratin. It functions to keep the snake cool and protected. The scales do not grow with the snake and so the skin must be shed as the snake grows! 2

2. Respiration Note: Sea Turtles can hold their breath for long periods. 3. Circulation Have lungs. Take in air by expanding rib cage. Three chambered heart. The single ventricle is partially separated by a septum. Blood stays mostly separate in the heart as it goes from lungs to heart to body and back. 3 Reptiles have lungs to breathe. The heart of a reptile is three chambered like a frog, but with a septum. Class Reptilia Characteristics

4. Nervous System Crucial is the Jacobson’s organs: Brain is less than 1% of total mass of animal. Brain is less than 0.5% of crocodilians. Most (sans snakes) have a tympanic membrane. Pits in the mouth that contain nerve endings sensitive to chemicals. To find prey, mates. 4 Reptiles have a very small brain, but have good coordination and eyesight. The have tympanic membranes for hearing and Jacobson’s organs for sensing prey and such. Class Reptilia Characteristics

Classification of Reptiles Order Key Characteristics Examples Numbers of Species SquamataDisarticulating lower jaw Some venomous species Snakes Lizards 6600 TestudinataBodies encased in protective shells Turtles Tortoises 300 CrocodiliaFour chambered heart Some parental care Alligators Crocodiles 21 RhynchocephaliaSpiny dorsal crestTuatara2 5

“ Snakes! Why did it have to be snakes?” 3 Types of Movement: 1.Serpintine: Winding across the ground or in water. 2.Concertina: Tight “S” shape and extending forward. 3.Sidewinding: Moving sideways! 4.Rectilinear: Scrunching and then extending forward. Snakes have 3 methods of movement; serpintine, concertina, sidewinding, and rectinlinear. 6

Feeding of Snakes: Note: Snakes are strictly carnivorous and feed on living prey! Types of Venon: Eat prey whole by dislocating their jaw. Some have heat sensing pits between their eyes and nose. They have Jacobson’s organs. Some nonvenomous snakes use constriction to kill prey. Some have venom in glands that is fed to fangs. 1.Neurotoxin: Attacks nervous system. 2.Hemotoxin: Attacks tissues. Snakes eat prey whole. Some have heat sensing organs, some constrict their prey, some have venom. There are two types of venom: neurotoxin and hemotoxin. 7 “ Snakes! Why did it have to be snakes?”

Lizards How are Lizards different from Snakes? Which are Venomous? 1.Two pairs of limbs. 2.External ear openings. 3.Eyelids which can close. 4.Lizards have same scales on belly as rest of body. Gila Monster Mexican Beaded Lizard Lizards have two pairs of limbs, ears with which to hear, eyelids, and scales on belly. There are two Lizards which are venomous. 8

Turtles Characteristics of Turtles: Turtles have are hard shell called a carapace and a lower shell called a plastron. There are land dwelling tortoises and water dwelling turtles. 9

Tuataras Facts that explain why it is not a lizards: Live only in a few islands around New Zealand. Holes in skull. Unique tooth arrangement. Has light sensing third “eye” in top of head. Tuataras are not considered lizards due to the holes in the skull and unusual tooth arrangement. They have a third “eye” and live near New Zealand. 10

Crocodilians Interesting Facts: Largest reptile. Crocodiles close their nostrils when capturing prey. All are oviparous. Crocodilians are the largest reptile alive today. They are top predators. They are egg layers. 11

The End!!!! 12