Summary: | Locomotor activity rhythms of one hyalid and six talitrids were deterermined extending published rhythms to species in three new ecotopes previously not examined in this way: eulittoral – the hyalid, Apohyale prevosti (H. Milne Edwards 1830) with a circatidal rhythm, supralittoral/palustral – the talitrid, ‘ Orchestia’ grillus Bosc 1802 and supralittoral/xylophagous talitrid, Macarorchestia remyi (Schellenberg 1950), where activity was random in both. A xylophagous-acclimated population of Platorchestia platensis (Krøyer 1845) living in a secondary ecotope also exhibited random activity. Endogenous diel rhthyms with maximum activity during darkness were present in the supralittoral wrack generalists [ P. platensis and Orchestia gammarellus (Pallas 1766)] and sand-burrowing specialists [ Americorchestia longicornis (Say 1818) and A. megalophthalma (Spence Bate 1862)]. The tentative order for talitrids examined here and in the literature, from high to low, in their susceptibility to passive, natural dispersal in wrack/driftwood is therefore as follows: O. gammarellus + P. platensis > O. mediterranea Costa 1853 > marsh-hoppers > sand-hoppers > driftwood-hoppers.
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