Field studies were carried out along a Mediterranean rocky shore to describe the foraging behaviour of the hermit crab Clibanarius erythropus, a common intertidal Diogenidae. The spatial strategy adopted during foraging activity was investigated through monitoring the movement of ten individuals, each followed for two hours. This revealed that hermit crabs maximized the space explored while in search of food and that shell type was one factor influencing the extent of movement. The evaluation of hermit abundance on different algal substrates provided clues to understanding the pattern of food utilization. This study shows that ‘generalist’ hermit crabs display a certain degree of selectivity, mostly foraging on assemblages of filamentous algae and corticated macrophytes. The conclusion is that C. erythropus selects substrates where good foraging can occur; whether hermit crabs eat within the selected substrates every food item they encounter or select food at the level of individual items is still an unanswered question.