What are imphibians?

It seems there might be a typo in your question. If you're referring to "amphibians," they are a class of cold-blooded vertebrates that typically begin their life in water as larvae with gills and then undergo metamorphosis to develop lungs for life on land. Amphibians include frogs, toads, salamanders, and newts. They are known for their permeable skin, which allows for respiration and moisture absorption, making them sensitive to environmental changes.