Amphibian
The word amphibian is derived from the latin word for "two lives". Amphibians have a two stage development; the larval stage and their adult stage. Amphibians differ from the other four classes in that those classes are born as smaller versions of their adult self. Amphibians are ectothermic ( which states their body temperature is regulated by the environment), and lack scales, hair or feathers.
Most amphibians start life with gills then as adults become air breathing, allowing their survival outside of an aquatic environment. However, amphibians such as the mudpuppy or salamanders, develop lungs and retain their gills allowing survival in aquatic and land environments.
Amphibians are said to be the link in the evolution chain between fish and reptiles. Amphibians use their skin and mouth for gas exchange in their respiratory process. Amphibians also have a three chambered heart. Both the right and left atrium empty into the one ventricle and then oxygenated blood is pumped from the left atrium into the brain, while the right atrium takes the deoxygenated blood to the skin and lungs which it receives more oxygen.
Amphibians reproduce sexually, and most require an aquatic environment for laying their eggs.
Most amphibians start life with gills then as adults become air breathing, allowing their survival outside of an aquatic environment. However, amphibians such as the mudpuppy or salamanders, develop lungs and retain their gills allowing survival in aquatic and land environments.
Amphibians are said to be the link in the evolution chain between fish and reptiles. Amphibians use their skin and mouth for gas exchange in their respiratory process. Amphibians also have a three chambered heart. Both the right and left atrium empty into the one ventricle and then oxygenated blood is pumped from the left atrium into the brain, while the right atrium takes the deoxygenated blood to the skin and lungs which it receives more oxygen.
Amphibians reproduce sexually, and most require an aquatic environment for laying their eggs.