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Reptiles Section 31.1 Animal Classification Invertebrates Sponges Cnidarians Worms Mollusks Arthropods Echinoderms - Order Squamata -Snakes and lizards - Order Crocodilia -Crocs and gators -Order Testudines (or Chelonia) -Turtles and tortoises Animals (cold-blooded) Fishes Amphibians Reptiles Endotherms Birds Mammals Ectotherms Vertebrates Phylum Chordata (warm-blooded) What is a Reptile? Class Reptilia – snakes, turtles, alligators, and lizards Stem reptiles – early reptiles that were the first animals to become adapted to life on land Evolutionary advantages reptiles have over amphibians Claws Dry skin (scales) Scaly Skin Unlike the moist, thin skin of amphibians, reptiles have a dry, thick skin covered with scales Scaly skin prevents the loss of body moisture and provides additional protection from predators Scaly Skin Because of their thick skin, reptiles are dependent on lungs as their primary organ of gas exchange Desert Horned Lizard Reproduction Most reptiles reproduce by laying eggs on land Some snakes give live birth to well-developed young Sea turtle eggs Gartner snake giving birth Anaconda Birth Reproduction Amniotic egg – provides nourishment to the embryo and contains membranes that protect it while it develops in a terrestrial (land) environment The egg functions as the embryo’s total lifesupport system Reproduction Parts of an amniotic egg 1. Amnion – a membrane filled with fluid that surrounds the developing embryo; it cushions the embryo and prevents dehydration Reproduction 2. Shell – The reptile egg is enclosed in a leathery shell Reproduction 3. Yolk – The main food supply for the embryo; its enclosed in a sac that is also attached to the embryo Reproduction 4. Albumen – the clear part of the egg; a source of additional food and water for the developing embryo Reproduction 5. Allantois – a membranous sac that stores the embryo’s wastes Reproduction 6. Chorion – a membrane that forms around the yolk, allantois, amnion, and embryo; the chorion and the allantois allow gas exchange for respiration Reproduction 7. Egg tooth – A reptile hatches by breaking its shell with the horny tooth on its snout; it falls off after hatching Reproduction All reptiles have internal fertilization Snakes and lizards have hemipenes Hemipenis – structure used to inject sperm into a female Cloaca – opening where the hemipenes is inserted; waste also exits the cloaca Reproduction Embryos develop after egg is laid Most reptiles provide no care for hatchlings, but female crocodiles guard their nests Reproduction Most reptiles lay their eggs under rocks, bark, and grasses; a few dig holes or form a nest In crocodilian species, both low and high temperatures result in females and intermediate temperatures select for males Reproduction In many turtle species, eggs from cooler nests hatch as all males, and eggs from warmer nests hatch as all females Skeletal Changes in Reptiles Reptiles have legs that are placed more directly under the body rather than at right angles to the body as in amphibians This makes walking and running easier Circulatory System Most reptiles, like amphibians, have threechambered hearts Crocodilians have four chambered hearts that completely separates oxygen-rich blood from oxygen-poor blood Circulatory System This separation supports the higher level of energy use required by land animals Ectotherms Reptiles do not inhabit extremely cold regions Many species of reptiles become dormant during cold periods in moderately cold environments (northern United States) How Reptiles Obtain Food Most turtles and tortoises are herbivores, and those that are predators prey on worms and mollusks How Reptiles Obtain Food Snapping turtles are extremely aggressive, attacking fishes and amphibians, and even pulling ducklings under water How Reptiles Obtain Food Lizards primarily eat insects The Komodo dragon, the largest lizard, is found on several islands in north of Australia (Indonesia) How Reptiles Obtain Food The komodo dragon is an efficient predator, sometimes even of humans Mouth is filled with deadly bacteria that is used to kill prey How Reptiles Obtain Food Some snakes have poisonous fangs A constrictor wraps its body around its prey Cobra vs Rat Snake Sense Organs Pit organs – heat-sensitive areas that enable snakes to detect air temperature brought by the presence of warm-blooded animals Sense Organs The tongue is used for smelling Jacobson’s organ – a pitlike sense organ on the roof of the mouth that picks up and analyzes airborne chemicals Turtles Order Testudines (or Chelonia) The dorsal part of the shell is the carapace, and the ventral part is the plastron The vertebrae and expanded ribs of turtles are fused to the inside of the carapace Turtles Most turtles can draw their limbs, tail, and head into their shells for protection against predators Turtles have powerful jaws with a beaklike structure that is used to crush food Turtles Tortoises Aquatic Eat insects and worms (some eat birds) Have claws Webbed feet Can live up to 60 years Terrestrial Eat fruits and insects Do not have claws Feet are not webbed; they’re round and stumpy Can live up to 150 years Crocodiles Order Crocodilia Crocodiles Long, slender, V-shaped snouts, Light olive brown coloration Found in saltwater and estuaries Estuary – a mixture of freshwater and saltwater Alligators Short, broad, U-shaped snouts Blackish coloration Found in freshwater Pictures of croc and gator Crocodiles Crocs and gators both have powerful jaws that can drag prey underwater and hold it there until it drowns Crocodiles Both lay eggs in nests on the ground Unlike other reptiles, these animals stay close to their nests and guard them Tiger vs. Crocs Lizards and Snakes Order Squamata Most lizards have four limbs Snakes have no limbs and lack the bones to support limbs Exception are pythons and boas which retain bones of the pelvis The claw is known as a spur Lizards and Snakes Some snakes even swim and climb trees Have ridges on its belly used for gripping (like tire treads gripping the road) Lizards and Snakes Snakes usually kill their prey in one of three ways 1. Constriction – snakes wrap themselves around their prey Examples: boas, phythons, and anacondas Boa Lizards and Snakes 2. Venom – These snakes use poison to paralyze or kill their prey Rattlesnakes, cobras, and vipers Lizards and Snakes 3. Non-poisonous and non-constricting snakes get their food by grabbing it with their mouths and swallowing it whole Bull Snake vs. Ground Squirrel Cobra vs. Mongoose Cat vs. Snake
