Amphibians
The amphibians group, once called "batrachians", is a group of four-legged vertebrates, somewhere between fish and reptiles seeking to come inland. Most amphibians spend part of their lives in the water (larvae) and part of their lives on land, this being caused by a metamorphosis controlled by their thyroïd hormones. Frogs lose their tails during this metamorphosis and develop members. But even the species most adapted to life on land must return to an aquatic, softwater environment to lay their eggs. To reproduce, they generally couple, but without an internal insemination. The male deposits its sperm where the female lays its eggs. Some exceptions do exist, like the Alpine salamander, a salamander adapted to the mountain (the Alps), whose female, after an internal insemination, keeps the embryons in its genital tubes (this is known as vivipary).
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| Tree frog | Toad |
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| Edible frog | Male newt |
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| Fire salamander (Salamandra salamandra) |