In a very old sample, I came across a beautiful example of phototaxis in a chrysophyte alga (perhaps Onchromonas?). I noted that if I dwelled in a single area on the slide too long, it soon became completely flooded with these alga. A fun observation, but it made it very difficult to capture the Heterophrys amoeba also present in the culture. You can clearly see how effective the capture mechanism of this amoeba is in the images below. With the speed and strength of the chrysophyte, it blows my mind that such a delicate looking organism can ensnare and immobilize their prey!
The video is approximately 4500 images acquired over 5 minutes with a Zeiss Axiocam MRc; I have the video playing back at 100 frames per second. The still images were acquired with a Nikon D70 and flash illumination. Both were with a 63x/1.4 Plan-Apo lens and DIC.
http://www.youtube.com/watch?v=EhptfJK73_s
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Images acquired on a Zeiss Axiovert 200M.
