What is an amphibian?

What is an amphibian?

• A. A cold-blooded vertebrate that begins life in water with gills and metamorphosis to life on land.
• B. A warm-blooded vertebrate that gives birth to live young.
• C. A mammal with hair and mammary glands.
• D. A bird with feathers.

Answer: (A)

Amphibians are vertebrates that regulate their body temperature through the environment (ectothermic) and have a life cycle that begins in water. They typically hatch or are born in water with gills and an aquatic form, and many undergo metamorphosis to develop lungs, limbs, and other features that let them live on land. This combination of starting life in water with gills and then transforming for life on land, plus their moist, permeable skin, is the hallmark of amphibians. The description that fits this pattern describes a cold-blooded vertebrate whose early life is aquatic and which undergoes metamorphosis to a terrestrial form. In contrast, mammals are warm-blooded and give birth to live young, and birds are warm-blooded and have feathers.

Amphibians are vertebrates that regulate their body temperature through the environment (ectothermic) and have a life cycle that begins in water. They typically hatch or are born in water with gills and an aquatic form, and many undergo metamorphosis to develop lungs, limbs, and other features that let them live on land. This combination of starting life in water with gills and then transforming for life on land, plus their moist, permeable skin, is the hallmark of amphibians. The description that fits this pattern describes a cold-blooded vertebrate whose early life is aquatic and which undergoes metamorphosis to a terrestrial form. In contrast, mammals are warm-blooded and give birth to live young, and birds are warm-blooded and have feathers.