Ant on a wire (hair)

Jun 10, 2016 • 9:24 AM UTC

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Microorganisms

Manu Prakash

I am a faculty at Stanford and run the Prakash Lab at Department of Bioengineering at Stanford University. Foldscope community is at the heart of our Frugal Science movement - and I can not tell you how proud I am of this community and grassroots movement. Find our work here: http://prakashlab.stanford.edu

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I love tools. The right tool for the right job makes all the difference. But sometimes you have to invent tools. And that’s so much fun; since if it does not work well – you can blame yourself and start all over again.
Here I share a simple method to mount small insects (say an ant) live under a Foldscope using a “human hair” as a tweezer.
The problem I was trying to solve was to image ants live. Often, if they are squeezed – the behavior I see is very different and it’s impossible to study them under a Foldscope for a long time. So, here is a simple way I can easily “almost levitate” small insects without damage to the ant for my study.
What you will need for this method:
1) One long hair. Pull it out of your head or your friends. Try different hair and you might find one works better than the other (do you know why).
2) tooth pick
3) paper or glass slide and tape.
The idea to levitate an ant is to make a loop/knot in a piece of hair; and have an ant be trapped in the same. After that, you can suspend the ant in a glass slide and image it for hours under a Foldscope

Now, to do this with a live ant and get it to fit inside a tiny knot in a hair; you need a trick. For a short while, the ant should not move. You can easily achieve that by using “surface tension” of water. Take a drop of water on your finger, and bring it close to an ant walking by. One its trapped on the moisture on your hand; put it down – and make a simple knot in the hair. Stretch the hair to bring the loop to be of a small size and loop the ant inside. Pull the hair further and tighten your grip. Hair has a stiffness so that after a certain size, it’s very hard to actually squeeze further. This allows you to make a loop that fits the abdomen or neck of an ant; without hurting the same.
Mount the hair on the glass slide as shown below with some tape.

So; now since I have the ant mounted – I images it for hours; and learned how it grasps with its mandibles. Take a look; those jaws moving in and out. You can also see the heart in the abdomen and blood being pumped around everywhere.

I was curious if it could cut the hair and free itself; but that did not happen.
I was so curious about the jaws – I imaged them later (I had to sacrifice the ant for this) by squashing the ant between glass slide and a cover slip.