Monday, April 22, 2019

Whats that crawling out of your eyelids? Parasites? Arrrgh!

Whats that crawling out of your eyelids? Parasites? Arrrgh!

demodex parasites Whats that crawling out of your eyelids? Parasites? Arrrgh!

These close-up animal photos show tiny microscopic parasites, known as Demodex, that live within the hair roots on our bodies. Despite their gruesome and alien like appearance they are reasonably harmless. We wouldn’t even know that they exist were it not for the skill and dedication of photographers who specialise in taking pictures of very tiny animals for our photo library. The technique they use is called scanning electron microscopy (SEM) and to get animal pictures as amazing as the one shown here, is an art in skill, dedication and patience.

The first stage with SEM animal photography is to capture and prepare the specimens. Due to the high vacuum within the SEM imaging chamber, specimens must be completely dry. For most small animals, this is done by immersing them in ethanol. Some microscopy photographers like to slow freeze their specimens first. This is so that the animals die in as natural a body position as possible. Freeze it too quickly and the animal could end up twisted, distorted or even worse, rupture and lose various body parts.  After all the water has been removed the specimens are coated with an ultrathin layer of conductive metal – usually gold.

The gold plated critter can then be imaged within the SEM machine. But the hard work does not stop there, the photographer will zoom and angle around the specimen in order to find the best viewpoint, then captures the image he wants. By zapping the specimen with electrons and detecting where those electrons bounce back, the SEM machine creates an extraordinarily detailed black and white image. The photographer must now become artist and spend a great deal of time colouring the black and white picture to add to its appeal. The result is this and many others of microscopic animals, plants and material objects that are too small to be seen in detail by the naked eye.

So the next time you scratch that nagging itch on your head, think about what might be causing the itch in the first place.


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