|A153 Amphibians &
These animals 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
fishlike, 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.