. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 252 PATRICIA L. TIMKO anus rectum tJ) "~ intestine § n O Q. intestine stomach- esophagus mouth. 0 10 20 30 FIGURE 4. Clearance rate of food through the Dcndrastcr gut. The ordinate shows the position of the food in the gut and represents linear distance (actual distance varied with the size of the animal; see Fig. 3). Solid circles represent the rate of passage for a meal of Artemia force fed to the sand dollars, open circles represent the rate for a meal of Artemia fed free choice to the sand dollars, and the
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 252 PATRICIA L. TIMKO anus rectum tJ) "~ intestine § n O Q. intestine stomach- esophagus mouth. 0 10 20 30 FIGURE 4. Clearance rate of food through the Dcndrastcr gut. The ordinate shows the position of the food in the gut and represents linear distance (actual distance varied with the size of the animal; see Fig. 3). Solid circles represent the rate of passage for a meal of Artemia force fed to the sand dollars, open circles represent the rate for a meal of Artemia fed free choice to the sand dollars, and the solid triangles represent the rate for a meal of Navicula force fed to the sand dollars. items, such as algal filaments and single crustacean prey, were moved without visible evidence of a, mucus string. If the food item was several mm long {, pieces of (surf grass) or small polychaetes), it was moved by a coordinated rowing motion of the ambulacral tube feet in contact with the food. The period of a stroke and retraction was about two sec. When food reached the buccal cavity, it was drawn in by the buccal tube feet. Small items could be taken in by ciliary currents. In the case of foods several milli- meters long, the buccal spines (which normally lay flat over the buccal cavity) were raised to admit the large item. Food was drawn past the peristomal membrane by the teeth, which thoroughly ground the food prior to swallowing. The time for the entire sequence from capture to ingestion varied from 5 to 30 min, with active prey requiring more time than nonmotile items. The average time from prey :apture to ingestion was about 15 min, and the teeth usually masticated the pre/ for another 15 min prior to swallowing. Rejection response Selective rejection of food occurred at two sites: the test surface and the Y junction of food grooves near the mouth (Fig. 2). If an item which Dendraster. Please note that these images are extracted from scanned page images that ma
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
