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Amphibians. Amphibians. AMPHIBIAN=GREEK FOR AMPHIBIOS WHICH MEANS “DOUBLE LIFE” ECTOTHERMIC VERTEBRATES HIBERNATE OR ESTIVATE DEPENDING ON CLIMATE. Three Orders of Amphibia. Anura-frogs and toads Urodela-salamanders and newts Elongated bodies and tails

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three orders of amphibia
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 characteristics of amphibians
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 dividedheart-atrium is divided, but the ventricle is not.
  • Cutaneous respiration -most supplement oxygen uptake by respiring through skin
  • 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
double loop circulation
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
amphibian heart
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
amphibian reproduction
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


cold blood cold blood

smooth or slimy skin warty and dry skin

Frogs have:

Toads have:

frogs and toads
Frogs and Toads

92 species

in USA

3,300 species

in the world

amphibian habitats
Amphibian Habitats



lakes, ponds, marshes

rivers and streams

why we care
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

why we care18
Why We Care

3. Amphibians provide benefits to humansi.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).

4 frogs as bio indicators
4. Frogs As Bio-indicators

1) double life--amphibious

2) permeable skin

3) absorb and concentrate toxins--biomagnification

4 frogs as bio indicators20
4. Frogs As Bio-indicators

Biomagnification: a process in which retained substances become more concentrated with each link in the food chain

external malformations
External Malformations
  • extra or missing limbs
  • branching limbs
  • spikes or protuberances
  • missing eyes
  • abnormal webbing
internal malformations
Internal Malformations
  • reproductive
  • digestive
  • urinary
causes of malformations
Causes of Malformations
  • genetic origins
  • parasite disruption of limb formation
  • chemical contamination
  • viruses
  • ultraviolet radiation
  • physical trauma (predation,


Trematode (flatworm) cysts have been demonstrated to cause problems in limb bud development in tadpoles

Dr. Stanley K. Sessions, Hartwick College

possible chemical contaminants
Possible Chemical Contaminants
  • Agrochemicals
  • heavy metals
  • acid rain
  • chlorofluorocarbons (CFCs)
types of agrochemicals
Types of Agrochemicals
  • herbicides


  • pesticides


  • fertilizers

Dr. Stanley K. Sessions,

Hartwick College

types of agrochemicals34
Types of Agrochemicals

applications of the herbicide atrazine have led to egg mortality and tadpole deformities (Hazelwood 1970)

Dr. Stanley K. Sessions,

Hartwick College

correlations to human health concerns
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 pesticideapplication
  • UV radiationresults in blindness and skin cancer in humans and other animals; DNA damage in developing frog eggs
where have all the frogs gone global amphibian decline
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
global population declines
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).

global population declines38
Global Population Declines
  • Increasing ultraviolet radiation
  • Pollution by chemicals
  • Acid rain
  • Pathogens
  • Parasites
  • Introduction of non-native species
global population declines39
Global Population Declines

Amphibian declines occurring in

locations where habitats relatively



Gastric Brooding Frog

last seen in wild in 1980s

global population declines40
Global Population Declines

Monteverde, Costa Rica:

Golden Toad

last seen 1988

global population declines41
Global Population Declines

Other places experiencing declines include:

Puerto Rico




U.S. Rocky Mountains

Cascade Mountain Range in Washington,

Oregon, and California