Amphibians

Amphibians, members of the class Amphibia, are cold-blooded vertebrates including frogs, toads, salamanders, and newts. All amphibians spend part of their lives in water and part on land - they are born with gills which some retain for their entire lives, while others outgrow them as they transform into adults and become permanent land-dwellers.

There are approximately 8,100 species of known living amphibians, all united by several unique traits:

• They typically have a moist skin and rely heavily on cutaneous (skin-surface) respiration
• They possess a double-channeled hearing system
• They have green rods in their retinas to discriminate hues
• They have pedicellate (two-part) teeth

Amphibians are the most threatened class of animals because they are extremely vulnerable to environmental threats such as climate change, pollution, and disease due to their porous eggs and semipermeable skin.