1. Amphibians

2. Characteristics of Amphibians
Amphibians are eukaryotic, heterotrophic vertebrates
They have thin, smooth, moist skin. Some of them have fish-like scales and none of them have claws.
They are ectothermic (coldblooded).
They have external gills and lungs.

3. Characteristics of Amphibians
Most amphibians have a two-part life cycle.
They complete a metamorphosis.
The embryo develops into an aquatic larva called a tadpole.
The tadpole breathes through feathery external gills.
The tadpole develops lungs and limbs during maturation.

4. Fossil Record Amphibians evolved from ancient ancestors of lungfish.
Early amphibians gave rise to reptiles (reptiles evolved from amphibians).

5. Adaptations to Land
Amphibians were the first vertebrates to face the challenge of life on land.
They are found in moist environments which prevents dehydration.
They absorb and lose water through their skin. They do not drink water.

6. Modern Classification
The three major groups of amphibians are:
Caecilians (resemble worms/snakes)
Salamanders (includes newts)
Frogs and Toads

7. Caecilians Structure and Function
Caecilians are legless and are shaped like worms or snakes
Most caecilians have thin, moist skin, while some have bony scales
Many have small eyes beneath the skin and are blind.

8. Caecilians
Habitat
Caecilians are found only in tropical environments (Asia, Africa, South America).
They make up the smallest percentage of amphibians.
They live in damp soil.
Caecilian Facts Video

9. Salamanders and Newts Structure and Function
They are the most prehistoric amphibians.
They have a slender, long body and tail
They have four short legs.
Their cells can regenerate some body parts (limbs and organs).
They can be aquatic or terrestrial. The terrestrial salamanders develop lungs. The aquatic ones retain gills (few).

10. Salamanders and Newts Habitat
Most live under stones or logs in damp wooded areas.
Aquatic salamanders never leave the water.

11. Frogs and Toads External Structure and Function
They are highly adapted for life on land.
They have powerful leg muscles for fast escapes.
Three eyelids:
Fleshy upper-eyelid
Thin lower-eyelid
Nictitating Membrane (Goggles)
For use underwater
Allows frog to see clearly

12. Frogs and Toads Vocal sac for calling (males) Webbed feet (True frogs)
Adaptation for swimming
Toe pads and webbing (Tree frogs/arboreal)
No webbing (Toads)
Paratoid glands – to release poison (Toads)
Warts (Toads)
Raised skin
Rougher, drier skin

13. Frogs and Toads Internal Structure and Function Teeth - two sets
Maxillary teeth
Vomerine teeth
Point inward to prevent prey from escaping
Tongue
Attached to the front end of the mouth
Glottis – air passage to the lungs
Esophagus – for swallowing food (whole)
Fat bodies – used for storing fat during hibernation or breeding

14. Frogs and Toads Liver Heart Made up of three lobes (sections)
Surrounds the heart
Heart
Two chambers/single loop system (tadpoles)
Three chambers/double loop system (adults)

15. Frogs and Toads Habitat
They are found all over the world (from deserts to rainforests)
Some are arboreal (tree frogs).
They make up 90% of all amphibians.

16. Amphibian Videos Giant Salamanders Rain Frogs Tree Frogs
African Bullfrog Fight