Bousfield's phylogenetic--systematic scheme (Bernice P. Bishop Mus. spec. Publ. no. 72 (1984)) for the family Talitridae has given renewed impetus to comparative physiological studies on representatives of his different morphological groupings within this, the only amphipod family with truly terrestrial constituents. Our comparative review of talitrid physiology presented here reveals the ecological adaptation of extant species. This has been set against Bousfield's view of the evolutionary history of the group in an attempt to produce a comprehensive and realistic organismic biology. The beachflea and sandhopper genera are highly modified for life in the supralittoral zone. The former group has given rise to euterrestrial amphipods which are to a certain extent physiologically pre-adapted for more rigorous terrestrial environments. Their success, however, compared with a more ancient landhopper group that invaded land directly (via the leaf litter of newly established angiosperm rainforests in the Cretaceous) may have been limited not solely by desiccation stress but also by more severe osmo- or iono-regulatory constraints.