the mean density of the needle-like setae for both size groups of U. vocans borealis
(Table III).
A total of 29 measurements were made of the time both Uca species remained on the
surface during the 4-day, 10 h field observations. U. lactea lactea spent 232.0134.5 s
whereas U. vocans borealis 118.277.2 s on the sediment surface. The results of a twosample
t test showed that U. lactea lactea spent significantly ( p0.05) between air and sediment temperatures was found among the four regions
of the study site. Thus, the data showed that the carapace temperature of both
U. lactea lactea and U. vocans borealis on the surface was slightly higher than the
aerial temperature while that in the burrow was lower than the sediment temperature.
For both Uca species, the mean carapace temperature was 0.46–0.66C higher when
the crabs were exposed to air on the surface than in the burrow (Fig. 4). Paired t-test
showed that the observed temperature difference was statistically significant in
U. vocans borealis, (n¼8, p¼0.009) and U. lactea lactea, (n¼8, p¼0.002). Results
of a two-sample t test showed that U. lactea lactea also had a higher carapace temperature
than U. vocans borealis both on the surface ( p0.05) between
the slopes and elevations of the regression lines of changes in percent body water loss
with time for the two Uca species under different conditions of relative humidity.
In general, percent body water loss varied linearly with relative humidity for both
Uca species, with a faster loss rate at lower relative humidity (Fig. 5). Under relative