1. Amphibians

2. Amphibians AMPHIBIAN=GREEK FOR AMPHIBIOS WHICH MEANS “DOUBLE LIFE”
ECTOTHERMIC VERTEBRATES
HIBERNATE OR ESTIVATE DEPENDING ON CLIMATE

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