Amphibians and reptiles are often confused, so they are treated together. "Amphibian"
comes from the Greek amphi, meaning "both," and bios, meaning "life." It has two
meanings. First, the animals physically change. Reproduction is accomplished through
external fertilization. The female spawns her eggs in water where they are fertilized
by the male. After hatching, most amphibians undergo a dramatic change known as
metamorphosis. They slowly change from fish-like, water-dwelling animals to ones
better suited for life on land. Fins and gills become legs and lungs. The most
well-known example is the change from tadpole to frog. Second, the term also refers
to these animals first living in the water and later on land. Reptiles reproduce
by sexual intercourse and internal fertilization, just like mammals. Amniotic
eggs develop within the mother's abdomen. Once they are sufficiently developed,
the mother lays them and they hatch. However some reptiles give birth to live
young.