1. Zoology
Phylum Chordata
Class Amphibia

2. General Characteristics
First vertebrates on land
4000 species
Strong skeleton to support body weight
Nostrils for breathing through nose
3 chambered heart
Air breathing lungs
Carnivorous diet
Eardrum
Eyelids

3. Important accommodations needed for land because of…
Oxygen content
Density
Temperature regulation
Habitat diversity

4. Donovan Period
400 million years ago
Mild temperatures and cycles of drought then heavy rainfall, then drought
Unstable environment when many pools evaporated, only those able to acquire atmospheric oxygen survived
Gills would collapse, dry, and lose function
Lobe-finned fish and lungfish were at an advantage
A kind of lung (extension of pharynex)
Bones in fins are like that in arms and legs or early amphibians
Came to land to escape predators or get food

5. bony or cartiliginous structures in lobed fin undergoing modificaiton
limb bones of early amphibians
Fig , p. 462

6. 3 Orders of Amphibians
1. Urodela
Tailed ones
Salamanders, newts, mudpuppies
400 species
Some are entirely aquatic and some live on land
Most walk by bending side to side
Usually internal fertilization – female picks up sperm packet, spermatophore, and inserts it into her cloaca
Born with gills, but these are usually lost in all but aquatic forms
Some do not have lungs or gills and use only skin and mouth for gas exchange

7. In-text, p. 463

8. 2. Anura
Tail-less ones
Frogs and toads
3500 species
More specialized for living on land
Use strong legs to hop
Flick tongue to catch insects
Defense from predators
Camouflage
Secrete mucus – bad tasting or poisonous
Many with poison have a bright color to warn predators

10. 3. Apoda
Leg-less ones
Caecilians
Nearly blind
Look like earthworms
160 species
Burrow through soil
Live in South America, Africa and Southeast Asia
Internal fertilization
Viviparous – live birth

12. Frog
Tadpole
Adults
Aquatic with gills
Gills and tail disappear
Lateral line
Lateral line
Develops legs
Finned tail
Some frogs do not go through the tadpole phase
Some are strictly aquatic and some are strictly land
Salamanders and caecilians resemble adults when born

13. Even land dwelling amphibians need a moist habitat
Need to stay moist
Some breath through skin and mouth because they have no lungs
Eggs do not have a shell and dehydrate in air
Male causes female to release eggs and spills sperm while she does this
Some incubate eggs on back, mouth or in stomach
Some are ovoviviparons and viviparons
Ovoviviparons – eggs hatch in uterus
Viviparons – young develop in uterus

14. Frogs are usually quiet, but may call during mating season
Many want to protect territory or attract females