. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. N. EMARG1NATA EGG CAPSULES 319 o - If 80 90 I DIAL CAPSULE LENG~- nrr Figure 7. Dry weight of empty capsular eases as a function of total capsule length (excluding stalk) for each laboratory population. Each data point represents one capsule. Least-squares linear regression equa- tions for each population are: Seppings: Y = - , r = , n = 27; Ross Islets, V = - r = , n = 33; Grappler Inlet, Y = - r = n = 28. fe
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. N. EMARG1NATA EGG CAPSULES 319 o - If 80 90 I DIAL CAPSULE LENG~- nrr Figure 7. Dry weight of empty capsular eases as a function of total capsule length (excluding stalk) for each laboratory population. Each data point represents one capsule. Least-squares linear regression equa- tions for each population are: Seppings: Y = - , r = , n = 27; Ross Islets, V = - r = , n = 33; Grappler Inlet, Y = - r = n = 28. ferences in capsule wall thickness among sites. Ross Islets capsules ranged in wall thickness from 50 to 76 ^m, while Seppings and Grappler capsules ranged from 71 to 92 ^m and 72 to 102 /urn, respectively. Longer capsules had significantly heavier dry weights for each laboratory population of snails (Fig. 7). Although the slopes of these site-specific relationships were not sig- nificantly different (ANCOVA for slopes; F = , P > ), the elevations did vary significantly (ANCOVA for elevations; F = ; P < ). These differences corresponded well with those in capsule wall thickness among populations, as thin-walled Ross Islets capsules weighed significantly less for a given length than thicker- walled capsules from the other two sites. Grappler capsules were also significantly heavier than Seppings capsules, again reflecting the differences reported above in wall thickness. Capsule wall strength. The force required to puncture capsule walls differed among the three laboratory popu- lations (Table I). Grappler capsules were significantly more resistant to puncturing than capsules from the other two sites (ANOVA, F = , P < ; Tukey Multiple Comparison Test. P ), despite the fact that Sep- pings capsules had substantially thicker walls (Fig. 5). The force needed to rupture capsules by squeezing also varied among laboratory populations (Table I). G
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
