Characteristics of Reptiles

1. Characteristics of Reptiles

2. Characteristics of Reptiles • Class Reptilia includes snakes, lizards, crocodiles, alligators and extinct dinosaurs. • The majority of reptiles are terrestrial and are adapted to a wide range of habitats. Crocodile or alligator? Gila monster Helodermasuspectum

3. Characteristics of Reptiles • Evolved from amphibians about 350 million years ago and dominated the Earth between 245 million and 65 million years ago—the Age of Reptiles (Mesozoic era).

4. Characteristics of Reptiles • Adaptations to terrestrial life include their dry, scaly skin (resistant to water loss and wear and tear) and their amniotic egg (consists of a hard shell and multicellular membranes, which encase the embryo in a secure, self0contained aquatic environment).

5. Characteristics of Reptiles • Are ectothermic. Regulate their body temperature by controlling how much heat they absorb. • Use lungs for respiration and have a circulatory system composed of two loops and a 3-chambered heart, in which one chamber is partially divided.

7. Characteristics of Reptiles • More advanced nervous system than amphibians. Most have a highly-developed sense of smell. Are equipped with a specialized organ sensitive to low concentrations of odors called the Jacobsen’s organ, located in the roof of the mouth.

8. Characteristics of Reptiles • Excrete nitrogenous wastes in the form of uric acid. In the body, uric acid is much less toxic than ammonia or urea. Thus, it requires little water for dilution, and reptiles lose only small amounts of water in their urine.

9. Characteristics of Reptiles • More than 5,000 species of modern reptiles divided into 4 orders: • Order Testudines: turtles, tortoises, and terrapins. Box Turtle: Geochelonenigravicina Galapagos tortoise Diamondback Terrapin Malaclemys terrapin Terrapeneornata

10. Orders of Reptiles • Order Squamata: lizards and snakes. Anole: Anoliscarolinensis Corn snake: Elapheguttata

11. Orders of Reptiles • Order Crocodilia: crocodiles and alligators. Siamese crocodileCrocodylussiamensis American Alligator Alligator mississippiensis

12. Orders of Reptiles • Order Rhyncocephalia: tuataras Sphenodonpunctatus

13. Stores nitrogenous wastes produced by embryo Surrounds all membranes and cushions developing embryo Thin membrane enclosing the fluid in which embryo floats Encloses the yolk A fat-rich food supply Provides protection from damage and evaporation of water from egg Contains proteins and water needed by embryo

14. Characteristics of Amphibians

15. Characteristics of Amphibians Modern amphibians share several key characteristics: • Most species change from an aquatic larval stage to a land adult form. This transformation is called metamorphosis.

16. Characteristics of Amphibians African Reed Frog Most have moist, thin skin with no gills. Skin is equipped with numerous mucus glands that supply a lubricant that keeps the skin moist in air.

17. Characteristics of Amphibians Larvae exchange oxygen and carbon dioxide through their gills and skin. Most adults lose their fills and respire through lungs and skin.

18. Characteristics of Amphibians All adult amphibians are carnivorous, with insects and other arthropods as the most commonly consumed prey. Most amphibian larvae are herbivores, feeding on algae, bacteria, or tiny green plants.

19. Characteristics of Amphibians Are ectothermic (external-heat). (Amphibians are ectothermic, which means their blood temperature rises and falls with that of the surrounding environment)

20. Characteristics of Amphibians Most have 4 pairs of limbs. Feet, if present, lack claws and are often webbed.

21. Characteristics of Amphibians Are oviporous. Eggs lack multicellular membranes or shells. They are usually laid in water or in moist places and in most species are fertilized externally.

22. Characteristics of Amphibians Poison Arrow Frog Many show parental care, guarding their eggs and keeping them moist.

23. Characteristics of Amphibians • Cloaca are the primary excretory organs. • A muscular cavity at the end of the large intestine through which digestive wastes, urine and eggs or sperm leave the body.

24. Characteristics of Amphibians A 3-chambered heart. Does not mix oxygen and deoxygenated blood very much. Little mixing increases the amount of oxygen that is delivered to the tissues.

25. Characteristics of Amphibians The amphibian circulatory system is divided into two separate loops. One loop carries blood between the heart and lungs. The other loop carries blood to the organs and tissues in the body and returns it to the heart. This “double loop” circulation delivers blood to the body faster. Double-loop circulation occurs in amphibians and is now used by them and all other vertebrates.

26. Characteristics of Amphibians The senses of hearing, smell, and sight are well-developed in most amphibians. Sound receptors are located in the inner ear, which is embedded within the head. Sounds are transmitted to the inner ear by the tympanic membrane, or eardrum.

27. Characteristics of Amphibians The olfactory lobes, which are the center of the sense of smell, are larger in amphibians than in fish. The eyes can blink and are covered by a transparent, movable membrane called a nictitating membrane. Additionally, there is a continuous communication among most areas of the body.