For each Uca species, 90 male crabs were captured from the field and transferred to the
laboratory. The carapace width of the captured U. vocans borealis ranged between 18
and 23mm whereas that of U. lactea lactea between 13 and 16 mm. In the laboratory,
each individual was put in a plastic container with perforations and placed within
a water table in which the water level was raised and lowered twice per day to simulate
high and low tidal conditions in the field. The salinity and temperature of the water was
maintained at 331ø and 221C, respectively, over the holding period. The crabs
were fed fish food and kept in the water table for three to six days prior to start of
the experiment.