observations were conducted once a
week over a period of eight weeks, thus including two periods each at
full, waning, new and waxing moon. Observation periods lasted for
24 h at neap tide and for 13–14 h at spring tide (11:00 a.m. until
11:00 a.m. with breaks during flood tide). Altogether 43 crabs were
observed, including 2 to 10 crabs on each occasion.