. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figure 3. (A| Bipinnana of Aatcnmi muuala, (B) auricularia of Parastichopus californicus, (C, D, E) view of broad side and (F) view of narrow side of ossicles at the posterior, left corner of the body of P. californicus, (G) and (H) ophiopluteus ofOphiiira tarsi, (I) echmopluteus ofDendrasterexcentricus. Cal- cite skeletons shown with polarizing filters partially crossed in (C) and (G) and fully crossed in (D, E, F, H, I). Scale bar is 400 ^m in (A, B. ) and 160/imin(C, D. E, F). Among echinoplutei, the stage of develop
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figure 3. (A| Bipinnana of Aatcnmi muuala, (B) auricularia of Parastichopus californicus, (C, D, E) view of broad side and (F) view of narrow side of ossicles at the posterior, left corner of the body of P. californicus, (G) and (H) ophiopluteus ofOphiiira tarsi, (I) echmopluteus ofDendrasterexcentricus. Cal- cite skeletons shown with polarizing filters partially crossed in (C) and (G) and fully crossed in (D, E, F, H, I). Scale bar is 400 ^m in (A, B. ) and 160/imin(C, D. E, F). Among echinoplutei, the stage of development affected density. In a sample of 32 larvae of S. francis- canus, the eight-armed larvae with two or fewer pedicel- lariae and no juvenile spines or plates (Fig. 4E) were less dense than both the earlier stage four- to six-armed larvae (Fig. 4C, D) and the more advanced stage eight-armed larvae with three pedicellariae (Fig. 4F. G). (Juvenile plates and spines were forming in some of the larvae with three pedicellariae.) The differences in density among stages were statistically significant (P < , Kruskal- Wallis test). Eight-armed plutei were similarly less dense than four-armed plutei within the species T. gratilla (Ta- ble I, Fig. 1 A, C) and D. excentricus (Table II). Very ad- vanced eight-armed plutei were more dense than four- armed plutei in S. pallidus (Table II, Fig. 4H). The den- sity changes during development were what one would have predicted from skeletal development. In early eight- armed stages of Strongylocentrotus species, the volume of skeleton relative to the volume of soft parts had de- creased because the heavy ends of the body rods had dis- appeared and because the soft parts had grown more than the skeletal rods (Fig. 4). Also in T. gratilla, the plu- tei at the eight-armed stage (Fig. 1C) were much more fleshy than the plutei at the four-armed stage (Fig. 1A), and the density of eight-armed T. gratilla was almost as low as the density of the
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
