1. Class Amphibia
17C

2. Taxonomy Phylum Chordata
Subphylum Cephalochordata- amphioxus or lancelet
Subphylum Urochordata- tunicates or sea squirts
Subphylum Vertebrata
Class Agnatha- jawless and cartilaginous, hagfish and lamprey
Class Chondrichthyes- cartilaginous, sharks and rays
Class Osteichthyes- bony fish
Class Amphibia- cecilians, salamanders, frogs, toads
Class Reptilia- snakes, lizards, turtles, tortoises, alligators, crocodiles, tuataras
Class Aves- birds
Class Mammalia- dogs, cats, lions, horses, cows, bears, giraffes, elephants, monkeys, kangaroos, humans, platypus, mice, beavers, seals, sea lions, walruses, whales, dolphins, porpoises, manatees, dugongs, anteaters, armadillos, sloths, bats, shrews, moles, hedgehogs…
Fish
Cold Blooded (Ectotherm)
Warm Blooded (Endotherm)

3. Class Amphibia Skin Lacks scales Richly supplied with blood vessels
Kept moistened by secretions from glands in the skin
Some secretions are poisonous to discourage predators
Chromatophores- cells that color the skin for camouflage or for warning
Functions as respiratory organ; blood vessels bring blood close enough to the environment so direct gas exchange can occur

4. Class Amphibia Feet No claws on the feet
Webbing may be present for those that spend time in water

5. Three Orders Order Apoda Caecilians Worm or snake-like body
No appendages
Tropical habitats
160 species
What’s the difference between apoda and annelida
Apoda have a backbone and jaws
Both have closed circulatory system

6. Three Orders Order Caudata Salamanders
Slender body with four identical limbs on trunk
Temperate habitats
400 species

7. Three Orders Order Anura Frogs and toads Large head Tailless
Short front limbs and large muscular hind limbs
Diverse habitats
3900 species

8. Class Amphibia “double life”
Metamorphosis- drastic change in habits and body structures
2-part life cycle is typical
Begins as an unshelled egg laid in or near water
After hatching, spends time in a swimming stage using gills for respiration, then develops into a terrestrial adult breathing with lungs

9. Mostly external fertilization, males discharge milt over eggs
Female lays jellylike eggs in the water (toads lay strings of eggs, frogs produce masses of eggs)
Mostly external fertilization, males discharge milt over eggs
Larval salamander resembles adult but with feathery external gills
Larval frog = tadpole
Oval body tapering to a slender tail. Flap of skin covers gills.
Gills degenerate and lungs develop
Limbs appear
Tail disappears
Digestive system changes from being able to digest mainly algae and plant material to where it can digest insects.

10. Respiration Gills in the larval stage
Lungs in the adult stage of terrestrial amphibians
Lining of mouth and throat
Skin (90-95% of respiration for certain lungless salamanders, also very important for adult frogs in the water)

11. Circulation Three chambered heart 2 atria and 1 ventricle
Left atrium receives oxygenated blood from the gills, skin, or lungs.
Right atrium receives deoxygenated blood from the body
Oxygenated and deoxygenated blood mix in the ventricle- not very efficient
Fish two chambered heart

12. Ectotherm
Hibernation- period of slow body processes, almost a lifeless state, burrow into the mud of a stream or lake during cold periods
Estivation- period of inactivity, escape heat by staying at the bottom of a pond, burrowing into the mud, or hiding in a cool place