. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 438 R. B. EMLET 3500- 3000- 2 2500 — u "i OC 2000 — UJ 1~ Ul < 1500 — Q O CO 1000- 500-. 1^ 400 ARM 1 1 z O (O z Ul 5s en UJ Ul oc 800 1200 1600 2000 LENGTH (microns) FIGURE 3. Expressed as Stokes' diameter, drag increases with arm length in two armed and four armed larvae. Reynolds numbers range from to 2 ||, two arms parallel to flow: 4 ||, four arms parallel to flow; 2 1, two arms normal to flow; 4 1, four arms normal to flow. The transformed empirical drag measurements (Fig. 2) are shown as (*). A*, two
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 438 R. B. EMLET 3500- 3000- 2 2500 — u "i OC 2000 — UJ 1~ Ul < 1500 — Q O CO 1000- 500-. 1^ 400 ARM 1 1 z O (O z Ul 5s en UJ Ul oc 800 1200 1600 2000 LENGTH (microns) FIGURE 3. Expressed as Stokes' diameter, drag increases with arm length in two armed and four armed larvae. Reynolds numbers range from to 2 ||, two arms parallel to flow: 4 ||, four arms parallel to flow; 2 1, two arms normal to flow; 4 1, four arms normal to flow. The transformed empirical drag measurements (Fig. 2) are shown as (*). A*, two 320 ^m long arms; B*, four 320 ^m long arms; C*, two 800 ^m arms; D*, four 800 ^m long arms. The shaded area of the graph is the range of greatest linear dimensions for larvae which move arms from a parallel ( ----- ) to a perpendicular (- -) ori- entation. The y-intercept is the diameter of the body region, approximately 260 I have modified this model for swimming in plutei and made the following assumptions. I assume that the ciliated band along the arms produces all of the locomotory forces and that the velocity profile is linear between the organism's surface and the cilia tips (Fig. 4). Reverse flow in the recovery stroke region is ignored, but Roberts (1981) shows that there is no reverse flow in this region in a freely swimming organism. Cilia in the band are approximately 25 nm long, and the band is 10 /um wide. These assumptions, the use of passive drag as a maximum estimate of the Fd component, and other assumptions to be mentioned later max- imize the forces and so maximize the predicted bending of the arms. Thus the hypothesis that stiffer spicules are necessary to prevent bending in longer arms is favored. L ider this model rejection of the hypothesis is a robust result, acceptance of the hypothesis is an inconclusive result. Fc, the force required to maintain the velocity gradient between the organism's surface and the tips of the cilia, is found by solving
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
