Talitrids are generally nocturnal, both to reduce desiccation and limit predation. They leave their shelter at night and migrate down the beach searching for food. They are preyed upon by shorebirds and staphylinid beetles, as well as unexpected predators such as foxes, raccoons, and burrowing owls. While juveniles generally live beneath wrack, adults dig burrows to depths of over 3 feet, which are guarded by males. Competition over females can lead to territorial fights between males, after which amplexis takes place in the winners burrow.
Females brood their eggs in an internal brood pouch, releasing fully active juveniles.
Much work has been done on orientation in talitrids, which seem to rely on subtle beach gradients and landmarks to navigate on wide beaches. They are non-specific scavengers, ingesting plant and animal material, as well as human debris such as paper. M. californiana is generally found on exposed beaches of medium and fine sand backed by dunes. M. corniculata is generally found on more sheltered pocket beaches with coarser sand. Insects and kin Beach wrack is inhabited by a wide variety of insect and other arthropod species.