The Microscopist's Mate, part 2 of many

Just for the record, all of what you find here, and in the other blogs in this series, is now available in fuller detail in my e-book Looking at Small Things.  Go to this link to find out more about how to get the free low-resolution copy, or the cheap high-resolution version: I'm a professional writer, so I like selling books, but I'm also a professional educator, so I like sharing ideas.

There's a similar free or cheap deal on offer for my Playwiths ebook as well, and to see what else I have been doing (LOTS!), go to this link.

This follows on from Part 1, obviously. If you don't read that first, you will be lost.

Today, the topic is sand, and microscopy using a cheap clip-on lens with a Samsung tablet.
The first sample is wind-blown sand from St Helier's Bay, Auckland, New Zealand.

No digital zoom, with the Go Micro

Full digital zoom applied to the Go Micro. This is part of the same field.

I got curious about the make-up of sand some years ago, when I tried to work out why some beach sand squeaks, when you walk on it.

That was when I discovered that there’s quite a lot of shell grit in some sands, little broken-up fragments of shell, as you can see in this shot of sand from Coller’s Beach near Mollymook in NSW. The shot on the right was taken with a fairly high-end microscope.

Fast-forward, and I was on a beach in New Zealand, two weeks ago, sampling up and down the beach. I had a thought: why not sieve the shoreline sediment and see what bits are there? For that, you need a sieve, and I remembered one of my favourite gadgets, a sieve jar: here’s how to make one.

A sieve is just a screen that only lets through something smaller than a certain size. A cat flap is a sieve that lets cats through, while stopping Dobermanns. Gardeners use a garden sieve to take out rocks and pebbles from garden soil, and so on.

I think I got the inspiration for the sieve jar from a gadget another scientist was using to investigate tardigrades. I use a 400-gram Vegemite or a 400 gram plastic peanut butter jar for this because these jars have a wide mouth, they are a good size and their lids are made of soft plastic.

To make my sieve, I take a soft plastic top from a jar, set it upside down on a piece of scrap wood and used a hammer and a small (1 to 1.5 cm) chisel to make a set of cuts that let me remove the flat top, leaving just an open ring. 

(Left) Cutting out the top of a jar lid to make a screw-ring. 

Then I used a square of flywire and attached it to the bottle, as shown in the picture below. Then, all I have to do is half fill the jar with leaf litter, and shake it gently over a white dish, watching to see what drops out, pootering my finds up so I can examine them. 

(And what’s a pooter? Try this link.)

Trim the corners, and you are ready to go. There is just one warning: small hands and jars made slippery in water, near rocks: can you see the problem? Plastic peanut butter jars make safer sieves for young users!

Most beach sand has just a few interesting shells, along with a lot of small sand grains, but I will come back to that when I get to looking at sand. This new use of the sieve jar occurred to me in February 2018: I expect that my readers will find new uses in their turn, just as I still do.

Once you have a sieve jar, the rest is easy, but choosing the right sort of beach is hard. Ideally, the sand grains will be fine enough to pass through the sieve, leaving you with a collection of broken bits to work through. I seem to get the best yields in sand 10 cm down in the wave zone.

This is the kit I take out with me, along with a notebook so I can
record where each of the jars was filled.

The trick is to fill the jar ¾ full of sand, rinse off the sand around the rim, screw the lid down, and then shake the sieve vigorously in the water. I put my other hand under the jar, so I can tell when sand stops falling out, then I tip or wash my catch into a second jar. I have a toolbox that carries six labelled jars and the sieve jar.

In the next shot below, I can see a quartz pebble, top right, a brown glass fragment, 1/3 of the way down, 1/3 of the way in from the left, and a small brown and white conical snail, 2/3 of the way down in the middle, fragments of dark blue or purplish shell, probably from cunjevoi.

I can also see several sea urchin spines (you may not see them, but you will see them below, shortly), bits of limpet shells, and somewhere in there, there was a tiny fish vertebra, or backbone segment. 

If you know the rocky shore shellfish, you will also see Bembicium, Melanerita and limpets, but who knows what else is hidden under the surface?

The trick to finding all the treasures is to spread the grit out as a thin layer in a white dish, and let it dry in the sun before you push the pieces around.

You can use a small paint brush for that, but I prefer to use tweezers, so that when something good comes up, you can pick it up and drop it into a Petri dish. There are sea urchin spines in the dish.

 In the pictures above, there was actually a bit much material, but it was still wet, so I just dumped it in there to take the shot. Notice the white dish, the tweezers and the Petri dish. The jar on the left is what I carried my catch home in.

   

My standard white dish is also good for sorting. The interesting bits go into the Petri dish, and now, you can see the sea urchin needles quite easily, but they will be clearer in the next two shots.

Now all we need is a microscope!

Shells are well within the reach of the Go Micro clip-on, or even a hand lens, so sand-sieving is one of those activities that can be adapted in many ways.

All of the pictures after and including the picture on the right were taken with a Go Micro clip-on — and these shots are just the beginning! Move in on your local shells, and see where it leads.

   

The shell is about 5 cm across (left, above), and on the right, it is as revealed by the Go Micro.

 

Looking at shell fragments

Now follows is a picture essay. First, here are the original subjects for the first batch:

Now here are some of them as seen with the Go Micro: the pictures represent an area of about 1 cm x 1 cm. From that, the reader can work out the magnification as they see it.

(Left and centre) sea urchin spines, (right) an unknown shell, possibly a limpet.

     

From the left, an unknown snail, a limpet and a piece of bottle glass. The identification as glass is confirmed by the stripy fracture pattern, called a conchoidal fracture.

A small limpet: specimens like this can be a bit disappointing.

When you find a shell with a small hole like this one, the animal that lived there was killed by something like an oyster-borer, also called a mulberry shell or Morula. The specimen on the left may have been killed by one of its own species, but we have no idea of how the specimen on the right died.

And by the time you are you are finished with examining sand (and maybe looking at some soil), your pond water should be ready to look at.  Next time, I will probably be looking at green slime, as I have had a set of culture bottles going: notice how they all get a free flow of gases, but are mosquito-proofed.

In other words, to be continued...

And Part 3 is now available.