Reading Essentials for Biology Glencoe (794133), страница 86
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They depend on external heat tomaintain their body temperatures within the range that they needfor their bodies to function. Reptiles may sun themselves to getwarm and then find shade when they get hot.Because reptiles depend on their environment to provide warmthfor their bodies, they do not live in extremely cold regions. Reptilesare commonly found in warmer or tropical regions. They also livein hot desert climates. Many species of reptiles become dormant,or inactive, during the colder months if they live in areas such asthe northern United States.NameDateClassSection31.1Reptiles, continuedHow do reptiles use their sensory organs?Reptiles have several sensory organs that help them detect danger.
The sensory organs also help them detect food. The heads ofsome snakes have heat-sensitive organs. These organs or pitsenable snakes to detect tiny changes in air temperature. Thesechanges are brought about when a warm-bodied animal comesinto a snake’s environment.Snakes and lizards also have a keen sense ofsmell. A snake will flick its tongue out. Thetongue picks up molecules of air. The snakethen pulls its tongue back into its mouth andmoves its tongue into its Jacobson’s organ. TheJacobson’s organ is a pitlike structure located inthe roof of the mouth in both snakes and lizards.Special cells in the Jacobson’s organ help the aniTonguemal identify and differentiate the smells found inthe air molecules.Jacobson’s organCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Diversity of ReptilesThere are four orders in the class Reptilia.
Snakes and lizardsbelong to the order Squamata. Turtles belong to the orderChelonia. Crocodiles and alligators belong to the order Crocodilia.Tuataras, lizardlike reptiles, belong to the order Rhynochocephalia.How are turtles different from other reptiles?Turtles are the only reptiles that have a shell made up of twoparts. The dorsal, or top, shell of the turtle’s body is called thecarapace.
The ventral, or bottom, shell is called the plastron. Thevertebrae and the expanded ribs of turtles are connected to theinside of the carapace. Most turtles have a two-layer shell. Theinner layer is hard and bony. The outer layer is made of hornykeratin. Keratin is a protein found in the exterior portion of theepidermis. Keratin helps to protect the living cells that are foundin the interior epidermis. In a few species of turtles, the shell ismade of tough, leathery skin. Most turtles can draw their limbs,their tails, and heads into their shells. They do this to protectthemselves against predators.
Turtles do not have teeth. They dohave powerful jaws that have a beaklike structure. Turtles usetheir jaws to crush their food.READING ESSENTIALSChapter 31379NameDateClassSection31.1Reptiles, continuedNot all turtles live on land. Some are aquatic. Turtles that liveon land are called tortoises. Tortoises eat fruit, berries, and insects.The largest tortoises in the world live on the Galápagos Islands.Some adult marine turtles swim long distances to lay theireggs. For example, green turtles travel from the coast of Brazilto Ascension Island in the Atlantic Ocean, more than 4000 km,to lay their eggs.3.
How do alligators andcrocodiles kill their prey?________________________________________________________________________4. Compare/Contrast Howare snakes similar to anddifferent from alligators?________________________________________________________________________________________________________________________380Chapter 31Crocodiles and alligators belong to the order Crocodilia. Theyare excellent, fast hunters. When they float in the water, onlytheir eyes and nostrils remain above water. Crocodiles have long,slender snouts, while alligators have short, broad snouts.Both crocodiles and alligators have powerful jaws and sharpteeth.
They catch their prey in their jaws and teeth, drag it underwater, and hold it there until it drowns. Crocodiles and alligatorscan breathe air with their mouths full of food and water. Thismakes them especially efficient predators. The American alligatorlives in freshwater.
It can be found in the southeastern regions ofthe United States. The American alligator can grow up to 5 mlong. The American crocodile lives only in salt water, and it canbe found in the estuaries of southern Florida. Crocodiles, such asthe Nile crocodile of Africa, can grow longer than alligators.Crocodiles and alligators do not migrate to reproduce.
Theylay their eggs in nests on the ground. They stay close to theirnests and guard them from predators. Several species hold theirnewly hatched young in their mouths and carry the young alligators or crocodiles to the safety of the water.How are lizards and snakes different fromother reptiles?Most lizards have four legs. Many species are adapted to hot,dry climates. Lizards are found in many places throughout theworld. Some lizards live on the ground while others burrow.Some lizards live in trees, and some lizards are aquatic.Snakes, unlike most vertebrates, do not have limbs. They donot have the bones to support limbs. Pythons and boas, however,do have bones of the pelvis.
Snakes have many vertebrae, whichpermit them to move quickly over grass and rough land. Somesnakes swim and climb trees.READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.How are crocodiles different from other reptiles?NameDateClassSection31.1Reptiles, continuedSnakes usually kill their prey in one of three ways. Constrictors,including boas, pythons, and anacondas, wrap themselves aroundthe prey and suffocate it. Venomous snakes use poison to paralyzeor kill their prey. These include rattlesnakes, cobras, and vipers.When these snakes bite their prey, they inject poison from theirvenom glands.
Most snakes are neither constrictors nor poisonous.They grab food with their mouths and swallow it whole. Snakeseat rodents, amphibians, insects, fishes, eggs, and other reptiles.What are Rhynchocephalia?There are two living species of this order. Both of the speciesare tuatara, and they are found only in New Zealand. Tuataras arethe only survivors of a primitive group of reptiles. Tuataras haveancestral features including teeth that are fused to the edge oftheir jaws. Most of the other species of this order died out 100million years ago.Copyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Origins of ReptilesThe ancestors of snakes and lizards are traced to a group ofearly reptiles, called scaly reptiles. Scaly reptiles branched offfrom stem reptiles.
Although the evolutionary history of turtlesis not complete, scientists have suggested that they may also bedescendants of stem reptiles. Dinosaurs and crocodiles are thethird group to descend from stem reptiles.Scientists used to think that birds arose as a separate groupfrom this third branch. Now there is fossil evidence that leadsbiologists to suggest that birds are the living descendants ofthe dinosaurs.READING ESSENTIALS5. What ancestor do snakes,lizards, turtles, and crocodiles have in common?________________________________________________________________________Chapter 31381NameDateClassSection31.1Reptiles, continued◗ After You ReadMini Glossaryamniotic egg: provides nourishment for theembryo; contains membranes that protectthe egg while it develops on landJacobson’s organ: a pitlike structure located inthe roof of the mouth in both snakes andlizards; special cells in the organ help identify and differentiate smells1. Read the terms and definitions in the Mini Glossary above.
Then use the space below toexplain why the development of an amniotic egg was critical to land animals.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________2. Use the Venn diagram below to show the differences and similarities between reptiles thathave limbs and those that do not.Reptiles with LimbsReptiles without LimbsCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.All ReptilesVisit the Glencoe Science Web site at science.glencoe.com to findyour biology book and learn more about reptiles.382Chapter 31READING ESSENTIALSNameDateClassSection31.2 BirdsSC.F.1.4.2 The student knows that body structures are uniquely designed and adapted for their function.SC.G.1.4.1 The student knows of the great diversity and interdependence of living things.◗ Before You ReadWhen you compare a bird and a reptile, there are many obvious differences.
Yet they may bedescended from a common ancestor. On the lines below, write ways in which birds and reptiles aresimilar and ways in which they differ.______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________◗ Read to LearnCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.What is a bird?There are more than 8600 species of modern birds in the classAves. Biologists sometimes refer to birds as feathered dinosaurs.Fossil evidence may indicate that birds evolved from small twolegged dinosaurs called theropods. Birds have clawed toes andprotein scales on their feet.
Fertilization is internal, and birds produce amniotic eggs that have shells. Amniotic eggs provide nourishment for the embryo developing inside. The shells offer someprotection for the embryo. All birds have feathers and wings, butall birds do not fly. Birds live all around the world, includingAntarctica, deserts, and tropical rain forests.IdentifyDetails Highlight the portions of text that provideinformation about bird flight.What are feathers?Feathers are lightweight, modified protein scales. Feathersprovide insulation and enable a bird to fly. Birds frequently runtheir bills or beaks through their feathers.
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