classification of amphibians

1. AMPHIBIANS
By
SAFIA AFRIDI

2. GENERAL CHARACTERISTICS
 Amphi- double; bios- life; living on land and breeding in
water
 Respiration by lungs, skin and buccopharynx
 Larval forms with lateral line system
 Exclusively fresh-water; no marine forms
Poikilothermic(cold-blooded)
 Exoskeleton absent
 Soft, moist and glandular skin without scales
 Homodont teeth
 Skull is dicondylic
 Protrusible tongue
 Cloaca present
 3-chambered heart(2atrium+1ventricle)

3. GENERAL CHARACTERISTICS
 R.B.C. large oval and nucleated
 Mesonephric kidneys
 Amphibians are ureotelic
 Middle ear with single rod like bone collumella auris
 Cranial nerves 10 pairs
 Sexual dimorphism found
 Oviparous and external fertilization
 Indirect development through tadpole larva mostly
 Anamniotes(extra-embryonic membrane amnion absent)
 Batrachology-study of amphibian
 Evolved from crossopterygian fishes

4. CLASSIFICATION

5. ORDER CAUDATA
 115-350 described species of salamendars
 Mostly terristrial, few lives in moist forest floor
and have aquatic larva
 Posses tail throughout their life
 Their size varies from few centimeters to 1.5m
 Members of the family Salamandridea are
commonly called newts
 Most salamanders have internal fertilization


6. ORDER CAUDATA
 Male produce gelatinous spermatophores that is
caped with sperm and deposited on the
substrate.
 Female pick up the sperm with cloaca and store
the sperm in spermatheca
 Eggs are fertilized as they pass through the
cloaca and are usually deposited singly, in
clumps or in strings.
 Larva posses external gills, a tail fins, larval
denitition and rudimentary tongue

7. ORDER CAUDATA
 The aquatic larval stage usually
metamorphoses in to terrestrial adult
 Other show incomplete metmorphosis and
are paedomorphc that is they became
sexually mature while still showing larval
characteristics

8. ORDER GYMNOPHIONA
 Member are caecilians
 160 described species
 They are worm like burrowers
 Feed on worms and other invertebrates in
the soil
 Body segmented because of folds in the skin
that overlie separations between muscles
bundles

9. ORDER GYMNOPHIONA
 Retractile tentacles between their eyes and
nostrils may transport chemicals from
environment to the olfactory cells in the roof of
the mouth
 Skin covers the eyes so caecilians are probably
nearly blind
 Fertilization is internal
 Larval stages are often passed in the oviduct,
other lay egg that develop either into aquatic
larvae or embryo that develop on land

10. ORDER ANURA
 Include 3500 species
 Frogs and toads
 Lives in moist environment
 Few may occur in dry dessert
 Adult lack tail
 Vertebrae fuse into a rodlike structure called
urostyle

11. ORDER ANURA
 Hindlimb are long and muscular and end in
webbed feet
 Fertilizartion is external
 Eggs and larva are typically aquatic
 Tadpole have well developed tail
 larva are herbivores and posses
proteinaceous beaklike structures used in
feeding

12. ORDER ANURA
 They undergo metaamorphosis
 Toad usually refers to anurans with relatively
dry and warty skin that are more terresitrial
than other members