Phylum Chordata
Subphylum Vertebrata
Class Amphibia
•Examples – Salamanders, frogs, newts
•Habitat – Aquatic when young, land & water
as adults
•Symmetry – bilateral
•Body plan – tube-within-a-tube
•Coelomates
•No segmentation
•Organ level of organization
Metamorphosis – body changes form
Larva – tadpole
•Breathe with gills
•Fins for swimming
•Fish-like circulatory system
Adult
•Breathe with lungs
•Lose tail and develop legs
•More advanced circulatory system
Frog metamorphosis
Protection from predators:
•Skin covered in mucus – keeps moisture
in; slippery to predators
•Skin loosely attached – predators can’t
grip them
•Camouflage
•Some are poisonous – brightly colored to
warn predators
Life Processes
•Support:
•Backbone and skeleton made of cartilage
•No ribs to protect internal organs
•Movement:
•Muscles; large hind legs specialized for
jumping
•Feeding and digestion:
•Diet – carnivores
•Process:
•Capturing food – tongue attaches at
the front of the mouth; 2 sets of teeth
to hold onto prey
•Swallowing food – close eyes and
push them down against roof of mouth
•Drinking water – they don’t – they
absorb water through their skin
•Digestion continued:
•Esophagus – moves food to stomach
•Stomach – stores food; digests protein
•Small intestine – digests most food
•Large intestine – absorbs water; packages
waste
•Liver – makes bile to digest fat
•Gall bladder – stores bile
•Pancreas – makes enzymes to digest fats,
proteins, and sugars
•Path of food – mouth  esophagus 
stomach  small intestine  large intestine
• Response:
• Brain – well-developed
• Nerves – well-developed
• Eyes – on top of head – can see and
swim
• Ears – located behind eyes
• Nose – on top of head – can breathe
and swim
• Tongue – attaches at the front of the
mouth
•Excretion:
•Kidneys – filter waste
•Bladder – stores urine
•Cloaca – removes waste
•Respiration:
•Gills when larva
•Lungs as adults
•Breathe through nares on top of head
•Internal transport:
•Cold-blooded – cannot control their
internal body temperature
•Heart – three-chambered (as adults)
•Closed circulatory system – blood
vessels
•Spleen – makes red blood cells
•Reproduction:
•Separate males and females
•Males attract female by making sounds
with vocal sacs under the chin
•Only sexually – no asexual reproduction
•Male mounts female, she releases eggs,
which he covers with a sperm solution –
fertilization is external
•Eggs swell and develop a protective
coating – looks like a mass of jelly in the
water
Frogs vs. toads:
•Frogs:
•two bulging eyes
•strong, long, webbed hind feet that are
adapted for leaping and swimming
•smooth or slimy skin (generally, frogs tend
to like moister environments)
•Frogs tend to lay eggs in clusters.
•Toads:
•stubby bodies with short hind legs (for
walking instead of hopping)
•warty and dry skin (usually preferring dryer
climates)
•paratoid (or poison) glands behind the eyes
•The chest cartilage of toads is different also.
•Toads tend to lay eggs in long chains.
(There are some toads (genera
Nectophrynoides), however, that are the only
types of anurans to bear live young!)