Phylum?Chordata 7 Classes: 1. Agnatha Jawless fish 2. Chondrichthyes Sharks, rays

3. Osteichthyes Bony fish 4. Amphibia 5. Reptilia

6. Aves Birds 7. Mammalia Mammals

Amphibia

What is an amphibian? A vertebrate that with some exceptions, lives in the water as a larva and on land as an adult. Uses gills as a larva, uses lungs as an adult. Lacks scales and claws. Has moist skin with mucous glands.

Theory: First amphibians to climb onto land probably resembled lobed-finned fish similar to coelacanth. The transition from water to land involved having legs, lungs to breathe air and protecting eggs from drying out.

Characteristics: Feeding: Tadpoles – filter feeders or herbivores Adults – Carnivorous Respiration: Tadpoles – Gas exchange through skin and use of gills. Adults – Lungs Circulation:

Excretion: Kidneys filter wastes from blood and form urine to be excreted.

Reproduction: External fertilization in most species Read on p 775 to fill in the blanks…

Movement: Larvae – wiggling their bodies and using a flattened tail.

Adults: Salamanders – walk, run move with S-shaped curves. Frogs and toads – Hind limbs enable them to jump. Tree frogs – have disks on their toes that serve as suction cups for climbing.

Response: Hearing: Through tympanic membranes (eardrums)

Large eyes that can move around in their sockets. Eye surface is protected by a transparent nictitating membrane. Located inside the regular eyelid. Protect eyes underwater and keep moist on land.

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