CLASS Amphibia Class Amphibia Amphibia means double life

CLASS: Amphibia

Class: Amphibia • “Amphibia” means double life: Land & Water • First vertebrates to leave the sea and inhabit land. Eggs must be kept moist • They must complete the fist stage of their lives in or near water • Reproduce sexually • Can absorb oxygen through their skin. • Unlike fish, they can go through metamorphosis to move on to land. • Fertilization of eggs is external (outside the body)

CLASSIFICATION • • Kingdom: Phylum: Class: Order: Family: Genus: Species: Animalia Chordata Amphibia

3 Orders of Amphibians • Order Anura – frogs & toads • Order Caudata – salamanders • Order Apoda – legless, wormlike amphibians

Amphibian Metamorphosis • Tadpoles: – – Have fins Have gills Two-chambered heart herbivorous • Adults: – – Legs, no fins Lungs, no gills Three-chambered heart carnivorous Amazon Horned Frog

Amphibians are Ectotherms • Body temperature changes with the temperature of the surroundings. • Become dormant when it is too hot or too cold • Usually burrow into mud until conditions improve.

ADVANTAGE OVER FISH: • Amphibians have a three-chambered heart! • Better circulation

Advantages: • One chamber receives oxygen-rich blood from the lungs and skin. • One chamber receives oxygen-poor blood from the body tissues • Third chamber pumps mixture to body tissues, lungs, & skin. • Most gas exchange takes place on moist skin of an amphibian! NOT THE LUNGS LIKE HUMANS!