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How to Use This Presentation • To View the presentation as a slideshow with effects select “View” on the menu bar and click on “Slide Show.” • To advance through the presentation, click the right-arrow key or the space bar. • From the resources slide, click on any resource to see a presentation for that resource. • From the Chapter menu screen click on any lesson to go directly to that lesson’s presentation. • You may exit the slide show at any time by pressing the Esc key. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter Presentation Transparencies Visual Concepts Standardized Test Prep Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Amphibians Table of Contents Section 1 Origin and Evolution of Amphibians Section 2 Characteristics of Amphibians Section 3 Reproduction in Amphibians Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 1 Origin and Evolution of Amphibians Objectives • Describe the three preadaptations involved in the transition from aquatic to terrestrial life. • Describe two similarities between amphibians and lobe-finned fishes. • List five characteristics of living amphibians. • Name the three orders of living amphibians, and give an example of each. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 1 Origin and Evolution of Amphibians Adaptation to Land • Preadaptations - are adaptations in an ancestral group that allow a shift to new functions which are later favored by natural selection. Lobe-finned fishes had several preadaptations that allowed them to transition to life on land. • • • • • bone structure pouches in digestive tracts for gas exchange nostrils higher metabolism efficient hearts Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 1 Origin and Evolution of Amphibians From Fin to Limb Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 1 Origin and Evolution of Amphibians Adaptation to Land, continued Characteristics of Early Amphibians Amphibians and lobe-finned fishes share many anatomical similarities, including: • similar skull • similar vertebral column • similar bone structure in fins and limbs • early amphibians had a large tail fin and lateral line canals Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 1 Origin and Evolution of Amphibians Characteristics of Early Amphibians Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 1 Origin and Evolution of Amphibians Adaptation to Land, continued Diversification of Amphibians • About 300 million years ago amphibians split into two main evolutionary lines. • One line included ancestors of reptiles, the other line included the ancestors of modern amphibians. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 1 Origin and Evolution of Amphibians Adaptation to Land, continued Diversification of Amphibians Today there are about 4,500 species of amphibians belonging to three orders: • Anura - includes frogs and toads • Caudata - includes salamanders and newts • Gymnophiona - includes caecilians (legless tropical amphibians) Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 1 Origin and Evolution of Amphibians Modern Amphibians Modern amphibians share several key characteristics • Most change from an aquatic larval stage to a terrestrial adult form, in a transformation called metamorphosis. • Most have moist, thin skin with no scales. • Feet, if present, lack claws and often are webbed. • Most use gills, lungs, and skin in respiration. • Eggs lack multicellular membranes or shells, are usually laid in water, and are usually fertilized externally. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 1 Origin and Evolution of Amphibians Characteristics of Amphibians Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 1 Origin and Evolution of Amphibians Modern Amphibians, continued Order Anura • Order includes frogs and toads. • Members may be fully aquatic, fully terrestrial, or amphibious. • Most reproduce in water, laying eggs that hatch into swimming larvae called tadpoles. • Larvae are herbivores. Adults are carnivorous and will eat any animal they can capture. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 1 Origin and Evolution of Amphibians Modern Amphibians, continued Order Caudata • Includes salamanders (may also be called newts). • Members may be fully aquatic, fully terrestrial, or amphibious. • Many reproduce in water. Some reproduce on land, with no swimming larval stage. • Larvae and adults are carnivorous. • Some have no lungs, and respire through their skin only. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 1 Origin and Evolution of Amphibians Modern Amphibians, continued Order Gymnophiona • Includes caecilians (legless amphibians that resemble small snakes). • Most are burrowing. They have small eyes beneath skin or bone, and are often blind. • All are carnivorous. • All are thought to have internal fertilization. • Some lay eggs which the female guards, others develop inside the female. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 1 Origin and Evolution of Amphibians Phylogenetic Diagram of Amphibians Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 1 Origin and Evolution of Amphibians Types of Amphibians Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Objectives • Relate the structure of amphibian skin to the types of habitats in which amphibians can survive. • Identify three adaptations for life on land shown by the skeleton of a frog. • Sequence the flow of blood through an amphibian’s heart. • Describe how a frog fills its lungs with air. • Describe the digestive and excretory systems of amphibians. • Discuss an amphibian’s nervous system. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Skin Amphibian skin serves two important functions: • Respiration - The skin is permeable to gases and water. Mucous glands secrete a lubricant that keeps the skin moist in air. • Protection - The skin protects amphibians from infection and secretes a foul-tasting or poisonous mucus that protects amphibians from predators. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians External Structure of a Frog Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Skeleton A strong skeleton supports the body of amphibians against the force of gravity. • Vertebrae interlock to form a strong, rigid structure. • Strong limbs assist with standing and walking. • Pectoral and pelvic girdles transfer weight to the limbs. • Skeletons of frogs are specialized for jumping and landing. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Skeleton, continued • Fused bones add strength to the forelimbs and hind limbs. • Thick arm bones and pectoral girdle absorb shock of landing. • Long hind legs allow frogs to jump farther. • Lengthened pelvic girdle and fused vertebrae add support. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Circulatory System The circulatory system is divided into two loops. • Pulmonary circulation - carries deoxygenated blood from the heart to the lungs and back to the heart. • Systemic circulation - carries oxygenated blood from the heart to the body and back to the heart. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Circulatory System, continued Three chambered heart: Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Amphibian Heart Structure Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Frog Heart and Double-Loop Circulation Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Respiration Amphibians use two forms of respiration • Pulmonary respiration - respiration through the lungs • Cutaneous respiration - respiration through the skin Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Respiration, continued Amphibians use positive pressure breathing, shown below. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Amphibian Lung Structure Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Respiration in Amphibians Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Digestive System • Includes the pharynx, esophagus, stomach, liver, gallbladder, small intestine, large intestine, and cloaca. • The upper part of the small intestine is called the duodenum. • The coiled middle portion of the small intestine is the ileum. • A membrane that holds the small intestine in place is called the mesentery. • Waste materials are stored in the cloaca and exit the body through the vent. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Digestive System, continued Accessory Glands • The liver produces bile, which is stored in the gallbladder and helps break down fat. • The pancreas secretes enzymes that help break down food into particles that can be absorbed by the blood. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Internal Structure of a Frog Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Excretory System • The kidneys are the primary excretory organ, and filter nitrogenous wastes from the blood. • Wastes combined with water are known as urine. • Urine flows from the kidneys to the cloaca and then to the urinary bladder, which branches off the cloaca. • Nitrogenous wastes are converted from ammonia to urea, which is highly concentrated and helps conserve water. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Nervous System • The olfactory lobes are larger in amphibians than in fish. • The cerebrum is responsible for behavior and learning. • The optic lobes process information from the eyes. • The cerebellum is responsible for muscular coordination. • The medulla oblongata controls heart rate and respiration rate. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Nervous System Sense Organs - • Larvae have a lateral line, most adults do not. • The eyes are covered by a nictitating membrane, a transparent moveable membrane that protects the eye. • Sound is detected by the inner ear. • Sounds are transmitted to the inner ear by the tympanic membrane, or eardrum, and the columella, a small bone that extends between the tympanic membrane and the inner ear. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Anatomy of a Frog Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 2 Characteristics of Amphibians Anatomy of a Frog (part 2) Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 3 Reproduction in Amphibians Objectives • Explain how a male frog attracts a female of the same species. • Discuss the reproductive system of a frog. • Describe the life cycle of a frog. • Describe the changes that occur during metamorphosis in frogs. • Identify two examples of parental care in amphibians. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 3 Reproduction in Amphibians Courtship and Fertilization • Males attract females with a mating call. • Females only respond to males of the same species. • The male clings to the female in an embrace called amplexus. • Eggs and sperm are released into the water. • Fertilization is external. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 3 Reproduction in Amphibians Courtship and Fertilization, continued Reproductive system • Male - includes two bean-shaped testes located near the kidneys that produce sperm during the breeding season. • Female - includes a pair of large ovaries containing thousands of tiny immature eggs. During the breeding season the eggs mature. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 3 Reproduction in Amphibians Life Cycle • When the eggs hatch, a tadpole is released. • The tadpole grows and slowly changes from an aquatic larva into an adult in a process called metamorphosis. • Metamorphosis is controlled by a hormone called thyroxine. • Some amphibians do not produce thyroxine and remain in the larval stage their entire life. • Some amphibians do not have a larval stage and hatch from the egg as small versions of the adult. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 3 Reproduction in Amphibians Life Cycle of a Frog Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 3 Reproduction in Amphibians Amphibian Life Cycle Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Section 3 Reproduction in Amphibians Parental Care Parental care increases the likelihood that the offspring will survive. • Some species guard their eggs until they hatch. • Some species sit on their eggs to prevent them from drying out. • The male Darwin’s frog carries the eggs in his vocal sacs until the larvae finish metamorphosis. • Female gastric brooding frogs swallow their eggs and the larvae mature in the stomach. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Multiple Choice 1. The forelimbs of vertebrates evolved from which structures in lobe-finned fishes? A. anal fin B. pelvic fin C. pectoral fins D. pectoral girdle Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Multiple Choice 1. The forelimbs of vertebrates evolved from which structures in lobe-finned fishes? A. anal fin B. pelvic fin C. pectoral fins D. pectoral girdle Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Multiple Choice, continued 2. Amphibians must lay eggs in water primarily for what reason? F. The eggs are not laid in nests. G. The eggs need oxygen from water. H. The eggs need protection from predators. J. The eggs do not have multicellular membranes and a shell. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Multiple Choice, continued 2. Amphibians must lay eggs in water primarily for what reason? F. The eggs are not laid in nests. G. The eggs need oxygen from water. H. The eggs need protection from predators. J. The eggs do not have multicellular membranes and a shell. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Multiple Choice 3. Metamorphosis must take place before amphibians are able to do what? A. swim B. live on land C. respire with gills D. feed themselves Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Multiple Choice 3. Metamorphosis must take place before amphibians are able to do what? A. swim B. live on land C. respire with gills D. feed themselves Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Multiple Choice, continued The figure below shows a longitudinal section, ventral view, of a frog heart. Use the figure below to answer question 4. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Multiple Choice, continued 4. Identify the source of blood flow in the section of the heart labeled 1. F. the body G. the aorta H. the lungs J. both lungs and body Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Multiple Choice, continued 4. Identify the source of blood flow in the section of the heart labeled 1. F. the body G. the aorta H. the lungs J. both lungs and body Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Multiple Choice 5. Anura : frogs :: Gymnophiona : A. toads B. newts C. caecilians D. salamanders Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Multiple Choice 5. Anura : frogs :: Gymnophiona : A. toads B. newts C. caecilians D. salamanders Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Multiple Choice, continued The figure below shows an artist’s rendering of Ichthyostega. Use the figure to answer the question that follows. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Multiple Choice, continued 6. Ichthyostega is an early amphibian. Which of the following characteristics is most likely to help it live on land? F. fishlike tail G. seven-toed feet H. four strong limbs J. lateral-line canals on the head Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Multiple Choice, continued 6. Ichthyostega is an early amphibian. Which of the following characteristics is most likely to help it live on land? F. fishlike tail G. seven-toed feet H. four strong limbs J. lateral-line canals on the head Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Short Response Modern amphibians are a diverse group, but they do have some common characteristics. Describe five key characteristics shared by modern amphibians. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Short Response, continued Modern amphibians are a diverse group, but they do have some common characteristics. Describe five key characteristics shared by modern amphibians. Answer: Metamorphosis from larva to adult; moist, thin skin; clawless feet; respiration with lungs, skin, and gills; shell-less eggs Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Extended Response Base your answers to parts A & B on the information below. Frogs breathe by a positive pressure system. Part A Describe how frogs move air into their lungs. Which part of inhaling is “positive pressure?” Part B Describe how frogs move air out of their lungs and into the atmosphere. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 40 Standardized Test Prep Extended Response, continued Answer: Part A The mouth floor drops, sucking air in. The nostrils seal and the mouth floor lifts (positive pressure), which forces air into the lungs. Part B: The body wall muscles and lung elasticity force lung air into the mouth, which makes the floor drop. The floor then lifts to force air out of nostrils. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.