. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. white light ^^ ~T» * ^ "" and whitf flow specimen t * water level white light \ collimator -V. -V-M-- propeller. expanded collimated laser beam (740 nm) expander-collimator lens system laser Figure 1. Apparatus for controlling water flow, (a) Side view of computer-controlled flume. Computer programs generate digital signals and send them to the digital-to-analog (D/A) circuit, where they are converted to analog signals to the 12 V DC flume motor. This system allows precise repetition of experimental flow regimes, (
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. white light ^^ ~T» * ^ "" and whitf flow specimen t * water level white light \ collimator -V. -V-M-- propeller. expanded collimated laser beam (740 nm) expander-collimator lens system laser Figure 1. Apparatus for controlling water flow, (a) Side view of computer-controlled flume. Computer programs generate digital signals and send them to the digital-to-analog (D/A) circuit, where they are converted to analog signals to the 12 V DC flume motor. This system allows precise repetition of experimental flow regimes, (b) Top view of flow tank showing positioning of video camera, lens system, light sources, optical paths, and specimen. Backlighting was provided, either by a laser in line with the specimen and the video camera or by a fiber optics lamp at an angle of about 25° to a line through the specimen and video camera. The dark-field lens system was used only with the laser. The two backlighting sources were not used simul- taneously. Both techniques provide a similar dark-field image in which naturally suspended particles in flowing seawater appear as bright points of light against a dark background, for flow visualization. Frontlighting by fiber optics was also provided for bright-field illumination of moving feeding appendages. in each consecutive video frame. Plotting the indexed be- havioral data against time produces a wave form, or cy- clical curve, that illustrates the changes in feeding com- ~ 6 to § 5 8s en % ' lot •\ - < 50 100 150 200 TIME (s) Figure 2. Repeating pattern of alternating accelerating and deceler- ating flows producing replicable, linear, water flow acceleration inducing porcelain crabs to switch from active to passive feeding. Feeding behavior was monitored only while flow accelerated. Flow deceleration simply reset the water velocity back to its original starting level, so that the next animal tested could be exposed to the same flow acceleration stimu
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
