Amphibians

Vertebrate Phylogenetic Tree Feathers Hair Amniotic egg Four limbs Jaws

Characteristics of Amphibians Phylum Chordata (vertebrates) Class Amphibia Live both on land and in water Adaptations for living on land Still need water to keep their skin and eggs wet

Three Groups Salamanders Frogs Caecilians Largest group of amphibians Legless Live in the tropics

Reproduction Amphibians need to return to the water to reproduce Eggs do not have a shell to keep from drying out Most frogs start their life as tadpoles

Metamorphosis Not all amphibians go through metamorphosis Tadpoles undergo many changes to develop into adult frogs Gills and lungs resorbed Tail absorbed and legs are grown Digestive, skeletal, nervous, and circulatory systems rearranged

External Anatomy Eye Mouth Forelimb Hindlimb Webbed foot Tympanic membrane- ear drum

Internal Anatomy Nervous system Digestive system Circulatory system

Nervous System Brain Spinal cord Nerves

Digestive System Mouth Esophagus Stomach Small intestine Large intestine Cloaca Liver- usually largest structure, three lobes Detox materials and produces some digestive enzymes

Urogenital System

Circulatory System Heart Dorsal aorta- large blood vessel along the back Veins- carry blood back to heart Arteries- carry blood away from heart