January 31, 2003

The Lovable Water Bear...

... and Other Spectacular Specks!

We are talking briefly about finding DJ something to look at with his new microscope. If you're not interested in this morning's topic, just clean your nails, maybe doodle us something on a napkin, we'll be done in a minute. This is just Weird Uncle Fred blathering about biology again, with a short treatise on pond scum (and you thought surely I couldn't do any worse than the soliloquy on compost, back in the summer!) You may begin humming now... DJ, come with me.

Now it's been a long time since I did what you're wanting to do, so I'll have to dig back into my memory to decide what to tell you. First of all, realize that you have the kind of microscope (I think, haven't had confirmation on this) that will let you see details of small things that are thin enough to let light pass thru. Something thick...like that dead fly my parents wanted me to look at... will just be a big black blob. One of his wings, on the other hand, will be a bit more interesting. Even a blade of grass will be too thick, so, think thin!

And the next thing you need to know is that your 'scope has a very small 'depth of field', meaning that what you see will be in focus only if it is flattened. Looking down into a standing drop of water on a slide would be like flying over a mountain of jello and looking for a cherry somewhere inside the center of it. Squash that mountain so it all lays in one plane, taking the mountain off the top of the cherry. Toward this end, you'll need some cover slips. If you don't have any, get plenty of them. If you have them, they have to be CLEAN! Another neat thing to have would be one or two 'depression slides'. More about that another time. Another good thing to have around would be some methyl cellulose, a thick clear goo that slows down the fast moving critters so you can study them, otherwise they zoom past your lens like Tom Petty in his race car... or is that Richard? Doesn't matter. They'll be zoooming by so fast, you won't be able to tell the difference.

Image courtesy of BioMEDIA ASSOCIATES http://ebiomedia.com/gall/gallery_main.html The most exciting thing in early microscope exploration is to see tiny living things do living things... eating, moving around in all sorts of odd ways, reacting to light, digesting their food... stuff they do all day, every day, all around you...even under your feet... and you weren't even aware that world existed, until you got your microscope! So, find a still puddle in a grassy place, or better yet, a pond. (You'll do way better with looking around STILL water than moving water).

Yes, I know ponds are all frozen where you live, so this is a bit of a problem. If you can find some vegetation near an edge, a clump of grass with wet roots, get that; and some of the muddy stuff on the surface of the bottom is good too. Put that in glass bowl (clear is best) along with some of the pond water or rain water (don't use tap water), set it in the sunlight in a warm (but not hot) place and 'incubate' your sample for a few days. Then you're ready to explore!

Don't get discouraged if your first winter pond sample isn't great. Lots of things go dormant in this kind of weather (including microscopists!) Some things you are likely to see after a few weeks of pond sampling:

Protozoans of all kinds. The kind covered with beating hairs (cilia or flagella) are amazing in their variety.

Small crustaceans called ostracods. These are like little shrimp inside two shells. Don't put a coverslip on this guy or you'll squash him!

Single celled algae, including diatoms, and filamentous algae, long stringy stuff often called 'pond scum'. These will all be green. And they may MOVE... even the filamentous ones. If you thought plants JUST SAT THERE, think again. Some little plant creatures move around like animals!

Flatworms. You can collect some with a bit of meat. This will tell you how.

Tardigrades. Water Bears. Neatest critters on earth. Find them in clumps of moss.

ASSIGNMENT:
__________________________

Learn how a microscope works.

Become familiar with the creatures you are seeing and be able to identify them with the group they belong to.

Study these images (especially Ciliates, Pond Water, and Whirling Animals) so you'll begin to understand where these creatures live, and where to look for them.

Go hunting for "Bears in your Backyard".


Happy Hunting, DJ. Let me us know what you're finding!


Posted by fred1st at January 31, 2003 06:34 AM | TrackBack
Comments

Another point worth mentioning. Buy or borrow a good microscope! If you buy a low quality scope from a toy store or or department store you will most likely just get frustrated. I think you have spend in the $100 range to get a decent quality scope - but it will last a lifetime.

Posted by: Chris at January 31, 2003 09:06 AM

This reminds me of my childhood and my first microscope. I collected some swamp water and discovered another world in a drop of water. That early fascination led to my career as a chemist. But the piont of this story is what happened to the swamp water in the bottle. My father, a chronic nose drop user, couldn't find his drops in his room in the middle of the night, but luckily found them in the den. A very loud gagging sound was heard thoughout the house. Many years later I confessed.

Posted by: Liska at January 31, 2003 12:07 PM

Dear Sir,

One mustn't forget the magnificent Loriciferans and Kinorhychs (like Tardigrades). Nor the face that many of these fascinating creatures can cause potentially fatal diseases. (Don't swim in Florida fresh water with nose-plug and other protection).

shalom,

Steven

Posted by: Steven Riddle at January 31, 2003 05:42 PM

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