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Presentation on theme: "Amphibians."— Presentation transcript:

1 Amphibians


3 Three Orders of Amphibia
Anura-frogs and toads Urodela-salamanders and newts Elongated bodies and tails Young have gills-some adults retain them Apoda-caecilians Tropical, burrowing amphibians Legless, wormlike

4 4 Characteristics of Amphibians
Legs-important evolution for living on land. caecilians have lost their legs as they adapted to burrowing existence Lungs-larvae have gills most adults breath with a pair of lungs with the exception of lungless salamanders Partially divided heart-atrium is divided, but the ventricle is not. Cutaneous respiration -most supplement oxygen uptake by respiring through skin

5 Lungs Lungs are internal -allows exchange of oxygen and carbon dioxide between blood and air Greater the surface area the greater the amount of oxygen can be absorbed Lungs are not as efficient as gills, but there is more oxygen in air than in water so lungs do not have to be as efficient

6 Double Loop Circulation
Due to moving to land and requiring more oxygen for their muscles, amphibians developed a double loop in their circulatory system Amphibians have pulmonary veins that deliver oxygen rich blood back to the heart and then to the remainder of the body

7 Double Loop Circulation

8 Amphibian Heart Sinus venosus delivers blood to the right atrium
Septum separates the amphibian ATRIUM into right and left halves Septum prevents the mixing of oxygen poor and oxygen rich blood Both types of blood are dumped into the ventricle Conus arteriosus has a spiral valve that helps to keep the blood somewhat separate

9 Amphibian Reproduction
Require water because eggs lack shells to prevent water loss External Fertilization-female releases eggs and male fertilizes externally-called amplexus Complete metamorphosis-egg, tadpole, young frog, adult frog

10 smooth or slimy skin warty and dry skin
Vs. Frogs have: Toads have: cold blood cold blood smooth or slimy skin warty and dry skin

11 Anuran Diversity

12 Frogs and Toads 92 species in USA 3,300 species in the world



15 Frogs and Toads

16 Amphibian Habitats forests grasslands lakes, ponds, marshes
rivers and streams

17 Why We Care Amphibians are a part of the planet’s bio-diversity.
2. Amphibians interact in interesting ways with each other and the environment, i.e. both prey and predators

18 Why We Care 3. Amphibians provide benefits to humans i.e. Gastric Brooding Frog of Australia might have provided answers for people suffering from gastric ulcers (Case of the Vanishing Frogs, T. Halliday and W. R. Heyer).

19 4. Frogs As Bio-indicators
1) double life--amphibious 2) permeable skin 3) absorb and concentrate toxins--biomagnification

20 4. Frogs As Bio-indicators
Biomagnification: a process in which retained substances become more concentrated with each link in the food chain

21 Malformed Amphibians

22 External Malformations
extra or missing limbs branching limbs spikes or protuberances missing eyes abnormal webbing

23 Internal Malformations
reproductive digestive urinary

24 Malformed Frog Pictures

25 Dr. David Hoppe, University of Minnesota-Morris

26 Dr. David Hoppe, University of Minnesota-Morris

27 Dr. David Hoppe, University of Minnesota-Morris

28 Dr. David Hoppe, University of Minnesota-Morris

29 Causes of Malformations
genetic origins parasite disruption of limb formation chemical contamination viruses ultraviolet radiation physical trauma (predation, people)

30 Trematode (flatworm) cysts have been demonstrated to cause problems in limb bud development in tadpoles Dr. Stanley K. Sessions, Hartwick College

31 Dr. Stanley K. Sessions, Hartwick College

32 Possible Chemical Contaminants
Agrochemicals heavy metals acid rain chlorofluorocarbons (CFCs)

33 Types of Agrochemicals
herbicides Maneb-fungicide pesticides propylthiourea fertilizers Dr. Stanley K. Sessions, Hartwick College

34 Types of Agrochemicals
applications of the herbicide atrazine have led to egg mortality and tadpole deformities (Hazelwood 1970) Dr. Stanley K. Sessions, Hartwick College

35 Correlations to Human Health Concerns
high nitrate levels (from fertilizers) in human drinking water and frog breeding ponds are hazardous human birth defects result from pesticide application UV radiation results in blindness and skin cancer in humans and other animals; DNA damage in developing frog eggs

36 Where have all the frogs gone? Global Amphibian Decline
a concern during the past decade frog declines widespread and well-documented possible causes include habitat destruction, increased UV radiation, and chemical contamination

37 Global Population Declines
Loss of habitat from filling in wetlands to create more farmland for crops, and to build more houses and roads (Case of the Vanishing Frogs, T. Halliday and W. R. Heyer).

38 Global Population Declines
Increasing ultraviolet radiation Pollution by chemicals Acid rain Pathogens Parasites Introduction of non-native species

39 Global Population Declines
Amphibian declines occurring in locations where habitats relatively undisturbed. Australia: Gastric Brooding Frog last seen in wild in 1980s

40 Global Population Declines
Monteverde, Costa Rica: Golden Toad last seen 1988

41 Global Population Declines
Other places experiencing declines include: Puerto Rico Ecuador Venezuela Brazil U.S. Rocky Mountains Cascade Mountain Range in Washington, Oregon, and California

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