. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 16 R. H. BREWER number of planulae attaching to plastic (2395) exceeds that for glass (84). Second, only 65 () planulae attach to the upper surface of plastic coverslips (also, as above), but the attached planulae are evenly distributed between under and upper surfaces on glass coverslips (40 and 44, respectively). Third, equal numbers of planulae attach to the dish bottom beneath the plastic and glass coverslips (139 and 134, respectively) showing again (see above), but indirectly, that both coverslip types are equally
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 16 R. H. BREWER number of planulae attaching to plastic (2395) exceeds that for glass (84). Second, only 65 () planulae attach to the upper surface of plastic coverslips (also, as above), but the attached planulae are evenly distributed between under and upper surfaces on glass coverslips (40 and 44, respectively). Third, equal numbers of planulae attach to the dish bottom beneath the plastic and glass coverslips (139 and 134, respectively) showing again (see above), but indirectly, that both coverslip types are equally accessible to the planulae. The contact angle, or surface wettability, affects planular attachment (Fig. 3). Planulae vary in their attachment to surfaces which exhibit a contact angle less than 19° (lens cleaner-coated coverslips, ± °; opal, ± °; and mica, ± °), and at angles greater than this, but including the data for opal for the lowest point, their relative attachment to the substrates available to them directly parallels the size of the angle (Y = + ; < P < ). The diameter of the planulocysts formed by the attaching planulae is also correlated with contact angle: the cysts formed on glass ( ^m) are smaller (F, ,96 = ; P ~ ) than are those formed on plastic or either of the siliclad-treated coverslips ( ^m; ^m; /um, respectively); there is no difference in size among these latter planulocysts (F2,i96 = ; < P < ). The contact angle for roughened plastic coverslips ( ± °) on which more planulae attach (see above) is larger than that of their smooth counterparts ( ± °) and is close to the contact angle determined for siliclad-coated coverslips ( ± °) on which most planulae settle (Fig. 3). On natural substrates to which planulae are exposed in the field, the contact angle on fresh scallop shell ( ± °) approximates that for opal, mica, a
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
