1. Body skin glabrous, glandular, non-scaly, smooth and moist.
2. Respiration is by gills in the larval stage and by lungs in the adult stage.
3. There are 4 clawless toes on the forefoot and 5 on the hindfoot.
4. They are cold-blooded ectothermic animals. That is, their body temperature changes with the rise and fall of the environment temperature.
5. The first stage of life lives in water and the adult stage lives on land. That is, they live a double life.
6. The heart has three chambers. The heart consists of two atria, one ventricle, one sinus venosus and one conus arteriosus.
7. Renal and hepatic portal systems are advanced.
8. Their body is divided into head, neck and trunk.
9. The crown of the head is connected to the spinal cord by two occipital condyles.
10. The nervous system is divided into three parts. Central, peripheral and automated. There are 10 pairs of carotid nerves.
11. They are unisexual animals. They are excreted.
12. Their life cycle includes the tadpole larval stage.
[key words to remember features: skin, gills, lungs, fingers, ectothermic, bivalve, heart, hepatic portal system, occipital condyle, nervous system, tadpole]