Adult lungless salamanders have four limbs, with four toes on the fore limbs, and usually with five on the hind limbs. Within many species, mating and reproduction occur solely on land. Accordingly, many species also lack an aquatic larval stage, a phenomenon known as direct development in which the offspring hatch as fully-formed, miniature adults. Direct development is correlated with changes in the developmental characteristics of plethodontids compared to other families of salamanders including increases in egg size and duration of embryonic development. Additionally, the evolutionary loss of the aquatic larval stage is related to a diminishing dependence on aquatic habitats for reproduction. The lift of this constraint allowed widespread colonization and diversification within a broad number of terrestrial habitats which is a testament to the high success and proliferation of Plethodontidae.