What are classes of vertebrates that uses gills and lungs?

The classes of vertebrates that use both gills and lungs include amphibians and some species of fish. Amphibians, such as frogs and salamanders, typically have gills during their larval stage and develop lungs as adults. Some fish, like lungfish, possess both gills for aquatic respiration and lungs for breathing air when necessary. This dual respiratory adaptation allows these organisms to thrive in varied environments.