What Are the Characteristics of Amphibians?

Video Transcript

"The question is what are the characteristics that make an amphibian. Amphibians have descended from fish and they have lost the scales but have retained some of the same properties but the difference is with amphibians that sets them apart are that they are, they have a usually a smooth and moist skin, toads are an exception, but a smooth and moist skin that they perspire through. They have poorly developed lungs and actually exchange oxygen through their lungs but also through their skin. Another thing about amphibians is that they're ectotherms and so they get their heat from external sources as the sun. So they will hibernate when the weather gets too cold and they will estivate in the summer if it gets too dry and warm. Amphibians also go through a metamorphosis in their life stage and so they have external fertilization and they have no true egg just like an egg membrane and when they hatch, they go through a tadpole stage and metamorphosize into the adult stage. So that's another difference with them. Most amphibians have four legs excluding some, but most have four legs with no claws. Another thing is their heart, their circulatory system, they have a three chambered heart versus a four chambered heart that we think of in mammals. And so amphibians are quite different and have some unique properties all to their own."