The Four-toed is Michigan's smallest salamander, with adults only reaching 4 inches maximum. Like the Red-backed, it is lung-less. But unlike the Red-backed, it is not very common. A reason for this is its restrictive habitat requirements for breeding. The female does not lay eggs directly in the vernal pool. Instead, it must find clumps of moss that overhang the edge of the pool. It lays it eggs within the moss and protects the eggs during incubation. When the larva hatch, they must then drop down into the water. Thus, adult Four-toeds never re-enter their natal vernal pools, although they still require them for breeding. Why they should have evolved this way is not clear, but it is plausible that, because of their small size, this is a defense against aquatic predators.