. The Biological bulletin. Biology; Zoology; Marine biology. 484 THEODORA C. PAULSON AND RUDOLF S. SCHELTEMA different ages. Each graph represents veHgers in the same size-category. The size-categories represent different ages that roughly correspond with the three developmental stages that have been described previously (Scheltema, 1962, p. 4, PI. I) except that the category in Figure 2 here overlaps the "early" and "inter- mediate" stages. Newly "hatched" veligers, those that had not fed on plankton prior to the experiment, are grouped separately (Fig. 1). Dunal
. The Biological bulletin. Biology; Zoology; Marine biology. 484 THEODORA C. PAULSON AND RUDOLF S. SCHELTEMA different ages. Each graph represents veHgers in the same size-category. The size-categories represent different ages that roughly correspond with the three developmental stages that have been described previously (Scheltema, 1962, p. 4, PI. I) except that the category in Figure 2 here overlaps the "early" and "inter- mediate" stages. Newly "hatched" veligers, those that had not fed on plankton prior to the experiment, are grouped separately (Fig. 1). Dunaliella is rarely the first choice of veligers of any size. In all but one case (D-1, Fig. 1), the percentage composition of Dunaliella is greater in the experi-. l! Figure 1. Choice among three different species of algal food by newly emerged veliger larvae of the gastropod Nassarius ohsoletus (Say). For explanation see text. mental mixture than in the control. On the graphs this is indicated by the fact that experimental points are closer to the Dunaliella vertex ("D") than the con- trol points. This becomes more marked with increasing size of the larvae. Experimental points are always further from the Cyclotella vertex ("C") than points representing controls. This shows that the percentage of Cyclotella remain- ing in the mixture always decreases and consequently that Cyclotella has been con- sumed by the larvae. Cyclotella is never the last choice of veligers of any size. Preference for Phaeodactylum is different for newly "hatched" than for older larvae. Figure 1 shows that the percentage composition of Phaeodactylum is greater in the experimental mixture than in the controls, while Figures 2 and 3 show the experimental composition of Phaeodactylum in per cent to be less than. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustratio
Size: 1686px × 1483px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectb, booksubjectzoology
