Thursday, May 14, 2009

Water flea





This rotund little water flea with a long snout, which is a species called Chydorus sphaericus, turned up in a moorland pool in Weardale but it's common in ponds and ditches everywhere. The appearance of water flea species can vary quite a lot, since some can grow extra protective spines on their carapace if they detect the presence of a lot of predatory midge larvae in the water, while others show seasonal changes in shape.

6 comments:

  1. These images are fascinating, and I like the video posted earler. Do you take the picture while viewing it on the cameras lcd screen? What magnification do you use. I'm very interested in giving this a go.

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  2. Hi Les,It's all a bit Heath Robinson. I set the camera to its longest focal length setting on the optical zoom, focus the microscope on the specimen, then hold the camera directly against the microscope eyepiece and - with luck - the animal is still in position and the image appears on the viewing screen. It's easy enough for static objects but for anything moving fast it's very hit-and-miss. Couldn't afford to do it with a film camera but there's no cost issue with digital - doesn't matter if only one in twenty images is OK!

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  3. Reminds me of the days when I kept tropical fish and used to get live daphnia and cyclops from the pet shop. Fascinating watching the way they move.

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  4. Hi John, yes, I know what you mean - the larger water fleas have that jerky kind of movement where they always seem to be struggling not to sink. This little species tends to scurry around at high speed, like it has urgent business to attend to.

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  5. Interesting. Thanks for reply. One last question. What is your light source, or is it built in to the m'scope.

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  6. Hi Les,the light source is built into the microscope. For fast moving objects like this water flea it needs to be turned up to quite a high level of brightness for a short-enough shutter speed; even then there's sometimes some movement blur e.g. in the limb at the bottom of the animal in the lower picture.

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