CLASS

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CLASS AMPHIBIA Frogs, toads, salamanders,
newts, caecilians
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• General Traits
• A. Amphibia means double life.
• B. Live part of life in/near water.
• C. Live on all continents except Antarctica

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• External Structures
• Skin
• 1. Glands keep skin moist
• 2. May be toxic to deter predators
• 3. Chromatophores-
• help change colors
• for camouflage.

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• Skeleton Locomotion
• A. Adapted for support against gravity.
• B. Some adapted for jumping
• C. Salamanders newts
• legs out to side of body-
• makes it harder to run fast.

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• Digestion/Nutrition
• Young amphibians- herbivores
• Adult amphibians- carnivores
• Land- detect prey by sight
• Water- detect prey by smell

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• E. Use tongue to capture prey in a flip grab
  mechanism.
• Tongue is sticky to ensure capture of prey.

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• Circulation-
• A. 3 chambered heart
• 1. Left atrium- brings O2 rich blood from
  lungs and skin
• 2. Right atrium- brings O2 poor blood from
  body
• 3. Both atria dump into 1 ventricle which has
  3 narrow chambers that keep blood somewhat
  separate.
• 4. Carotid artery takes O2 rich blood to
  brain
• 5. Pulmocutaneous artery takes O2 poor
  blood to lungs skin
• 6. Aortic arches carry mixture of blood to
  rest of body.

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Carotid artery
Aortic Arch
Pulmocutaneous artery
Rt atrium
Lt atrium
Ventricle
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• Gas Exchange-
• A. Young- external gills that dissolve during
  metamorphosis.
• B. Adults-
• 1. Subcutaneous- thru skin
• 2. Simple sac-like spongy lungs
• 3. Must live in/near water to help breathe

External gills
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• Nervous/Sensory-
• A. Brain
• 1. Forebrain- olfaction, color change,
  visceral function
• 2. Midbrain- sense information sent to
  different parts of brain
• 3. Hindbrain- motor coordination,
• regulation of heartbeat respiration
• B. Skin- receptors for temperature pain

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• C. Chemoreceptors in skin, nostrils, tongue,
  mouth detect mates food.
• D. Lateral line system present in young.
• Vision
• 1. Sight feeders
• 2. Eyes on top of head- see while submerged.
• 3. Rods cones in eyes- suggest they can see
  some color.
• 4. Nictitating membrane- 3rd eyelid that
  protects cleans eye.

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• Tympanic membrane
• Flat hearing organ behind eyes
• Picks up air vibrations, sends to
• Middle ear, inner ear, then brain

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• Temperature Regulation
• A. Ectothermic- depend on external sources of
  heat to control body temp.
• B. Methods to maintain temp.
• 1. Nocturnal
• 2. Live near water
• 3. Burrow in mud

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• Excretion
• A. Kidney
• B. Wastes passed thru ureter to bladder to
  cloaca
• C. Cloaca is common area for passage of liquid
  waste, solid waste, gametes.

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• Water conservation very important
• a. Nocturnal
• b. Live near water
• c. Tuck limbs under body to reduce surface
  area being exposed to sun
• d. May form cocoon of shedded skin
• e. Flatten body on moist surface to absorb
  water.

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• Reproduction Development
• A. Fertilization- external
• B. Development of egg- external
• C. No covering for eggs, so must be laid in
  water to keep them moist
• D. Breeding done in spring summer during
  rainy season.

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• Vocalizations
• 1. Attract mate
• 2. Establish territories
• 3. Warn of danger
• 4. Calls are species specific
• 5. Females reciprocate call to tell whether
  they are ready for mating
• 6. Males have vocal sacs to amplify sound.

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F. Males generally take care of eggs. Keep them
cleaned, moistened (land), protect from
predators, remove dead/ infected eggs.
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G. Metamorphosis 1. Eggs- millions enclosed
in jelly-like substance. Makes them harder
to eat.
Salamander eggs
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• Larvae- tadpoles
• External gills
• No limbs
• Tail
• Yolk sac- food for developing tadpole
• herbivores

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• Adult
• a. Has lungs
• b. 2 front legs
• c. 2 powerful hind legs (frogs)
• d. No tail
• e. carnivores

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ORDERS OF AMPHIBIANS
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• Order Caudata
• Ex salamanders, newts
• Have tail throughout life
• 2 pairs unspecialized legs
• Found in moist areas, under logs, leaf litter
• Reproduction- internal fertilization
• a. Male deposits sperm cap.
• b. Female picks it up holds it in a sac
  called spermatheca
• c. Lay eggs in strings or lumps
• d. Aquatic larva look similar to
• adults

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• Order Gymnophiona
• Ex caecilians
• No legs
• Worm-like with segments
• Live in tropical regions feed on worms
• Blind- skin covers eye
• Reproduction- internal fertilization
• Larva are retained in females where they scrape
  oviduct lining with fetal teeth.
• Born as miniature adults

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• Order Anura
• 1. Ex frogs, toads
• 2. No tails
• 3. Strong hind limbs, webbed feet, some have
  claws
• 4. Live in moist environments- some in desert
• 5. Reproduction- external fertilization
• Toads- dry, warty skin more inland
• Frogs- moist, smoother skin more close to
  water,

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• Amphibians in Peril
• Frogs and salamanders are disappearing fast!
• Factors that decrease their populations
• Clear cutting forests dry out their moist
  environments.
• Mining, drilling, agricultural industrial
  operations, urban sprawl destroy habitat.
• Acid rain (below pH 5) from air pollution kills
  eggs tadpoles.
• UV radiation from destruction of ozone layer
  kills eggs tadpoles.
• All forms of pollution may cause mutation of
  eggs/tadpoles. See next slide.

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DAILY QUIZ 2

• Frogs have a ____ chambered heart.
• a. 2 b. 3 c. 4
• Frogs and toads belong to Order
• Anura b. Caudata
• c. Reptilia
• Subcutaneous respiration occurs through
• a. Skin b. Lungs c. kidneys

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• Amphibians are
• a. Endothermic b. ectothermic
• The structure labeled below is the
• Nictitating membrane
• Tympanic membrane
• Vomerine membrane