© 1968 by The Society for Integrative and Comparative Biology
Transition from Water to Land in Amphipod Crustaceans
New Zealand Oceanographic Institute Wellington, New Zealand
Truly terrestrial Amphipoda are known solely in the Family Talitridae, the only family also found extensively in the supralittoral. Commonly, they are crytozoic inhabitants of the leafmold of tropical or southern cold-temperate forests. Except as recent introductions, they are absent from Europe and North America. There are a few records from Central America and the Caribbean.
The success of the talitrids in colonizing the land is considered due to invasion of leafmold direct from supralittoral debris. Leafmold provides an insulated niche with sufficient food and moisture for colonization with little modification. Apart from possible loss of pleopods, adaptations appear merely to continue trends already present in littoral species.
Present distribution can only partly be explained in terms of past geology. Leafmold species are derived from cosmopolitan supralittoral genera and may have arisen independently in different countries. Some widely-distributed species, e.g., Talitrus pacificus, may have been transported by man; accidental transplantation of terrestrial amphipods is known.
The Amphipoda have not achieved the terrestrial independence of the Isopoda; they are restricted to a fairly narrow niche. Some species have colonized grasslands but in circumstances which are not environmentally very different from leafmold.