Thursday, August 11, 2011

Ray the Rotifer!

While gazing through the microscope at yet more pond water, I was surprised to see this swim past my field of view (click for larger versions)....

It is evidently some kind of rotifer (according to Maxine Mowe) with part of its cuticle expanded into lateral 'wings'. The animal is able to open and close these wings, and even flap them somewhat.

Do you think that there's some resemblance to the chaps below?

Japan stingrays Manta Ray - Under

The resemblance may be misleading, though. The rotifer is about a quarter of a millimeter across, whereas these skates and rays can measure about a meter or more. The way that water behaves at microscopic scales is very different from the macroscopic scale that we (and these fishes) live in. For zooplankton, the dominant property of water is its viscosity, as opposed to its inertia. Where a manta ray would coast along for several meters after a flap of its mighty wings, this winged rotifer would instead come to an immediate halt. So what are those wings for, on the tiny rotifer? Looks like it's something for an enterprising student to find out.

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