A number of lineages of have evolved to live predominantly on land. Examples of terrestrial crabs are found in the families Gecarcinidae and Gecarcinucidae, as well as in selected genera from other families, such as Sesarma,
Terrestriality and migration
No clear distinction is made between "terrestrial", "semiterrestrial", and "aquatic" crabs.
Rather, a continuum of terrestriality is displayed among the true crabs, although most land-adapted crabs must still return to water to release their eggs.
Some species of terrestrial crabs can be found many kilometres from the sea, but have to complete annual
animal migration to the sea.
For example, following the
Indian Ocean monsoon, the Christmas Island red crab (
Gecarcoidea natalis) migrates
en masse, forming a "living carpet" of crabs. The crabs can travel up to in a day, and up to in total.
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.
Many crabs belonging to the family
Potamidae, which contains mostly freshwater crabs, have developed a semiterrestrial (for instance the genus
Nanhaipotamon) to terrestrial life history, and are sometimes independent of fresh water for reproduction (for instance the genus
Tiwaripotamon).
Ecology
Terrestrial crabs are often similar to
, since the
physiological changes needed for living in
fresh water are
for terrestrial living.
On some
oceanic islands, terrestrial crabs occupy the top of the
energy pyramid.
See also
External links
