Friday, 19 August 2011

Magnificent eyes of water fleas

Water Flea Eye

  All arthropods have very impressive eyes. Some of them are simple, some of them are exceptionally complex and consist of lots of individual photoreceptor units. Insects and crustaceans often have both, which gives them such a bizarre look.

  I've never seen anyone taking pictures of eyes of microscopic creatures like water fleas. That's a shame because I believe they have the most unusual structures. The creatures' eyes are surrounded by thick transparent shells. Basically, it's the same external shell that's covering the rest of the body. The most interesting feature that I am currently unable to show is that they can move those compound eyes, which brings about associations of aliens in space suits.

Water Flea Head

  At first I was taking pictures with DIC illumination and got what you see above. The lens for that picture is 100x and the image was resized down from original 4000px width. And of course it's a manual depth stack where I could position elements in a way that would reveal as much as possible. May be it's hard to see, but there's a eye-moving muscle at the bottom of the eye leading towards the body.

  The following picture was in my previous post but that's a larger version. As you see, darkfield illumination is generally more spectacular.

Water Flea Eye

  Here the space between the eye and the body surface is more visible.

  In the next example that's the same eye from the title picture of the post but from different angle

Water Flea Eye

  The rest is not as good in quality as previous ones but is worth seeing as it represents different species of water fleas. All previous eyes belong to Polyphemus pediculus, and the one on DIC image is Scapholeberis sp.

Ceriodaphnia sp.:

Water Flea Eye

  And the last one looks like daphnia, however I didn't ID it properly yet

Water Flea Eye

   All images are stacks of photos taken with Sony NEX-5 through Zeiss Axioscope A1 with 10,20 and 100x lenses.
   I assembled the whole bodies of these fleas and I will post it soon.

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