This amoeba was quietly living in his drop of water in a petri dish with a big pinch of moss from my yard in it, and enough water to keep it alive, when I sucked him up out of his livingroom with a pipette and put it on a slide.
It's not as easy as you might think to find them though, even in such a small thing as a drop of water. On the slide, I have prepared it with 4 dots of nail polish to form a square close to the middle of the slide itself, a 1x3 inch piece of glass. The dots, after they dry, are to hold the coverslip, which is 22x22mm square, off the actual surface of the slide by a very tiny amount, so as not to crush some of the bugs under it. One amoeba under that coverslip is like one human in a square mile of vacant plain. Not so easy to find.
And of course, I never know exactly what is in the drop of water before I look. Every time I prepare a slide, it's like looking into a new Fabergé egg. The technique, once the coverslip is on and the slide is ready, the cover pulled off the microscope and the light warmed up, is to start at one corner of the 22mm square area and scan down, then over one row and back up, and see what you've caught today. Some of it is still chance though, cause some of the bugs can move quite fast. Most of the smaller ones are free swimming and dart around so fast that it's impossible to follow them with the slow adjustments of the stage knobs. Others, like rotifers, like to use their toes to grab onto the glass of the slide or coverslip and inch along like an inchworm.
Amoebas are the same way. They like to have a surface to crawl on and make their way along. By sucking them up in a pipette, and then squirting them out onto a slide, it's inevitable that some will end up out in the middle of the pond with no surface to grab onto. And then they resemble a cat that is caught in midair, all his hair on end and tail and four legs spread out as far as he can reach.
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Many people don't know this, but there are quite a few different species of amoeba. Some even build silica shells to live inside of. And never forget, they are the most successful animal alive on the planet. But they all have this star reflex built into them. They send out pseudopods as far and wide as possible to try and grab onto any solid surface. As soon as they find a surface, they draw themselves to it and lose the star shape.
So as I scanned over the coverslip on this slide, and since amoebas are so small and slow moving, I have to use the 20x objective, or I would probably miss him altogether. At 10x, he's just a dot of dirt in with all the other flecks of sand and inert material. At first, this one just looked like a clump of dirt, but something was suspicious and made me take a closer look, then I saw it move. Not him actually, but the fine particles and organelles inside him were moving, and that's when I turned on the camera.
Here is a rather long video I recorded too
. It moves slow as an amoeba, but is interesting to watch as he finds and engulfs a large clump of food. And here are some of the stills I got.
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