A number of lineages of crabs have evolved to live predominantly on land.

[2] No clear distinction is made between "terrestrial", "semiterrestrial", and "aquatic" crabs.

[4] Only a few land crabs, including certain Geosesarma species, have direct development (the mother carries the eggs until they have become tiny, fully developed crabs), and these do not need access to water to breed.

[5][6] Many crabs belonging to the family Potamidae, which contains mostly freshwater crabs, have developed a semiterrestrial (for instance the genus Nanhaipotamon[7]) to terrestrial life history, and are sometimes independent of fresh water for reproduction (for instance the genus Tiwaripotamon[8]).

[9] On some oceanic islands, terrestrial crabs occupy the top of the energy pyramid.