FIG. 4. Correlation between osmotic pressure gradient
across the body wall and bran&al Na, K-ATPase enzymespecific
activity (ESA) in homogenates of Hemigrapsus nudus
gills 6,7 and 8. Crabs were acclimated 2 weeks in 50%,
75% or 100% sea water; data from crabs acclimated in 25%
SW are not included because of the high mortality in this
group (see Methods). Each open symbol represents a value
for gill 6,7 or 8 from an individual crab; each filled symbol
represents the mean values of 15-18 gills from five or six
crabs in each medium; error bars indicate f 1 SE. ANOVA
followed by Fisher PLSD analysis indicates that the effects
of Na, K-ATPase ESA on the osmotic gradient across the
body wall are not significantly different in gills 6, 7 and 8.