Micro-Flotsam Captured in Holographic Action Movies

The CD was invented while I was in high school. Late each night, my local Florida radio station used to showcase one newly remastered CD in its entirety, in a show called “Laser Holography.” A gravelly voice would invite us to ease back into our leather armchairs and surrender to the pure digital sound experience. Steve Miller or Bob Seger would ensue.

So imagine my surprise when I learned today that far from being a passe (and possibly cheesy) method of listening to classic rock, laser holography is totally brand-new. And you use it for watching killer plankton hunt down their prey inside a drop of water.

Researchers from University of Maryland and Johns Hopkins studied two kinds of tiny dinoflagellates from Chesapeake Bay. Don’t be fooled by their size: “dinoflagellate” means “terrible whip,” and once the scientists got the interference pattern from their backscattered collimated laser beam magnified and fed into a high-speed digital camera (creating a holographic image), they sure found out why.

The single-celled organisms flagellated their terrible whips, scooting through the water as they tracked down even smaller single-celled creatures. The holography kept everything in sharp focus “like being at NASCAR with a magical pair of binoculars,” according to lead researcher Robert Belas.

In the picture above, the dinoflagellate Karlodinium sidles up to an unsuspecting herd of plankton and then pounces. It scares the bejeezus out of all but one of them, which is too dead to be scared. The green line shows the stalker’s track; the inset pictures are snapshots of the action. Another species, Pfiesteria, took down its prey on raw speed alone.

Read all about it in Proceedings of the National Academy of Sciences: Digital holographic microscopy reveals prey-induced changes in swimming behavior of predatory dinoflagellates. All told, it’s a considerably more thrilling way to spend an evening than Take the Money and Run.

image: National Academy of Sciences of the U.S.A. and Florida Game and Freshwater Fish Commission