Tasty pavement? Nope. A goldfish cracker.

I was asked if I could make some microscope images for some K-6 students - everyday things that they might know. We happened to have some goldfish crackers at home so I brought one in to see what I could see.

The first step was to image the goldfish with a light microscope - in this case a Leica dissecting microscope with a digital camera attached.

A familiar sight to major snackers like me.  This is a double cheese-flavored goldfish.  I was a little disappointed  that it didn't have the usual impressed eye and smile (not really), but it did have a red dot of some sort on it that kind of looks like an eye to me.

This images shows a close-up of the surface of the cracker.  The arrows show some salt crystals on the surface.  At this magnification the cracker looks pretty greasy.

Next came the careful dissection of the goldfish. I was amazed that it didn't crumble when I sliced it in half longways with a razor blade - in anatomy what we call that a sagittal section.  The structure of the inside is much more flaky than the dense crust on the outside.

To see this little cracker up close and personal I took some small parts of it and put them in my scanning electron microscope - an Hitachi S-3400N SEM.

This first set of images are of the outside of the little goldfish.

This image shows the outer surface of the goldfish.  To me it looks very much like the surface of a parking lot - pebbles embedded in a tar matrix.  Magnification is 183x. 

The surface of the goldfish at 34x magnification. The red arrows indicate salt crystals.

Here is a closer look at one of the salt crystals at 170x magnification.  You can also see the different sized particles that make up the crunchy outer skin of the goldfish.  The strange area in the upper right of this image is an imaging artifact.

A salt crystal at 450x magnification.   

Here is another salt crystal at 451x.  There are some smaller crystals on its surface indicated by the red arrow.

A close-up of the small salt crystals shown in the previous image.  Note that this image is at 2,500x magnification.

The inside of the goldfish is very interesting.  While the outer crust is dense, the inside is full of little air pockets.  This gives the goldfish that delightful texture and crunch.  (I guess you can tell I like to eat this little guys.)

This image at 90x magnification shows the different densities of the outside and inside of the cracker.  The next images zoom in on the center of this specimen.  If you look closely you should be able to match up the areas.

At 243x magnification the inside of the cracker shows what might be considered craters. There are pieces of material, grains I am guessing, embedded in a smoother matrix.

This image is a close-up of an area to (right of center) in the previous image.  1,400x magnification.

At 42x this inside of the goldfish cracker becomes otherworldly.  The next image is a close-up of the lower right hand part of this image.

I really like this image.  If you were to show this image to someone they would never guess what they were looking at.  110x magnification.

A 200x magnification showing the both the inner and outer layers of the cracker. Notice that the salt is only on the outside of the cracker. (Red arrows)

Another image at 90x showing both the inside and outer layer of the cracker.  The image below is a close-up of the crater at the center of this image.

A crunchy hole on the inside of the cracker shown at 365x magnification.

Microscopy allows us to see a world that, though present, is often invisible to the naked eye.  I am continually amazed at how intricate and interesting these tiny worlds and structures can be, and a simple, cheesy goldfish cracker is no exception.

Electron microscopes require only tiny specimens since so much magnification is possible.  I am happy to report that I was able to eat most of the goldfish at the end of my observations.  Makes me wish I had brought more than one.

Murry Gans
Eastfield College Microscopy Lab
Mesquite, TX