AMPHIBIANS
Phylum:
Chordata
 Subphylum:Vertebrata
Class: Amphibia
Order
Gymnophiona Caudata
Anura
Common
examples
Caecilians
small group,
worm like,
Tropical, no
appendages
Frogs and
toads
Salamanders
and newts
Digestive System

Digestive system:

Complete

Most are carnivores

First animals with a “true” tongue (modified in
anurans into a flip-and-grab feeding mechanism)

Have vomerine and maxillary teeth used for
holding food rather than chewing.

Like the fish, have a common opening to the
digestive, reproductive and excretory systems
called the cloaca.
Respiratory System
 Larva
have gills
 Adult have lungs controlled by a
buccal pump
 Skin – cutaneous respiration

Adults also use cutaneous (across the skin)
respiration and buccopharyngeal (inside the
mouth) respiration.

Disadvantage of amphibian respiration is that gas
exchange can’t increase when metabolic demands
increase.
SKIN
 Smooth
and glandular (needed to keep skin
moist)
 Many
give off toxic chemicals
 Caecilians
segments
have folds in skin look like
External anatomy and skeleton
Long
flexible vertebrae
Possess a tail except anurans
which have their caudal (tail)
vertebrae fused into urostyle
4 limbs except caecilians,
anurans have very strong, long
hind legs
Circulatory System
 Double
looped; systemic=to the body
pulmonary= to the lungs
 Three
chambered heart: 2 atria and 1
ventricle
a
spiral valve helps divide and direct blood
from the ventricle into either the
pulmonary & systemic systems
Temperature Regulation
 Ectothermic
and usually nocturnal
 Behavior is to stay in moist, cool area
during hot part of the day, occasionally
bask in the sun to increase body
temperature.
 Tolerates a wide range of
temperatures
Nervous System :
 Forebrain
(cerebrum): smell, color changes
and visceral functions
 Midbrain: sight, also assimilates sensory
information
 Hindbrain : motor coordination
(movement); also regulates heart rate and
respiration
 Possess lateral line system
 Chemoreception:
through the nasal area,
mouth and skin
 Sight:
binocular vision which allows for depth
perception
 Nictitating
 Hearing:
membrane to protect eye
tympanic membrane; well developed
in Anurans, poorly developed in Caudata
Sounds

Vocalizations in anurans
 Advertisement
call: male to female, usually
amplified by the male’s vocal sacs.
 Reciprocation
 Release
call
 Distress
call
call: female back to male
Excretory System :
 Nitrogenous
waste in aquatic forms is
ammonia, In terrestrial forms is urea
 Major problem is osmoregulation
(controlling water loss)
Reproductive system:
 Dioecious
 Most
have internal fertilization
 Anurans
have external fertilization, they
use amplexus (copulatory grasp so male
can stimulate female to release eggs that
are then fertilized)