Choosing a Microscope

I got the following questions in response to one of our YouTube videos:

I want to start exploring microbes with a microscope but I just don't know how I can. Will I need a microscope with a x1000 magnification? Is that all I'll need? What kind of (cheap) microscope would you recommend?

National Optics makes high quality microscopes. From what I've read, it's worth it to spend the money on high quality optics. I decided on the MI-SP162 which is binocular (less eye strain) and is a nice, sturdy microscope with precision controls. I also paid extra for the Super High Contrast Objectives (ASC), and I'm very happy with the results.

You can see protoza with the 100x and 400x objectives, and even some paramecia with the 40x. I don't use the 1000x objective much because I don't like messing with the oil, but you need it to see bacteria. So far we've looked mostly at protoza which are more complex and interesting.

At first we got a microscope with a built-in camera but the resolution was low and the speed wasn't fast enough to take movies--the germs were just blurs. Now I just put a Canon digital camera (PowerShot SD800 IS) up to the eyepiece on a small tripod and that's how I take the movies. I works quite well.

Baby Bug

We went to Lake Poway a few weeks ago and collected some lake water (with scum, of course!) from the spot marked by the arrow. We didn't get around to looking at it until a few weeks later, and by then some insect eggs had hatched into larvae.

Below is a little guy that was swimming around. The video is only at 4x, and he was a few millimeters long.

It might be a damselfly larva, based on pictures I found by googling. Here's a useful page of other tiny aquatic creatures.

I have to say, baby bugs just aren't as cute as baby mammals.

Wacky Glass Walker

This is the last of the creatures found in Calvin's fish tank, and it reminded us of Wacky Wall Walkers. This is a ciliate that uses it cilia to walk along the top of the glass. Did it evolve this trait specifically for life in a fish bowl?

A quick google search on "ciliate walking on glass" came up with hypotrich, which this appears to be. The legs with which it walks are actually bundled cilia called cirri. What did people do before google? (spend hours in the library, I guess)

Another Rotifer

Here's another rotifer from the scum in Calvin's fish tank, along with his friend the worm. The video below the picture shows the two of them in action. You can see the rotifer mouth sweeping in food, the jaws chomping it up, and the toes wagging like the tail of a happy puppy.






Why are there so many rotifers (three found so far) in this tank? I read that rotifers are added to fish tanks because they eat up debris and keep it clean. Were these added to the pet store fish tanks? Have they continued to propagate and survived the multiple tank cleanings and water changings?

Another Paramecium

Here's another creature found in the scum of Calvin's fish tank--it's quite a zoo in there. I believe this one's a paramecium based on the cilia it swims about with and the contractile vacuoles which it uses to pump out excess water. The video is taken at 100x and you can see smaller bacteria swimming around it, apparently unaware that the paramecium feeds on their kind.

Rotifer Jaws in Action

Here's another rotifer found in the scum of Calvin's fish tank (taken at 400x). At the beginning, we see the rotifer just swimming around looking for food. We then jump to a clip of it eating. You can see the cilia at the mouth moving around to sweep particles into the mouth, and then you can see the jaws chomping it up! The jaws are in the middle of the animal, and look a bit like the mouth of a sabre-tooth cat.

Brown Oozy Worm

Here's another one of Harold's friends. (Harold is Calvin's fish, and we found lots of creatures living in the scum of his tank.)

This is some kind of brown oozy worm. Is it one gigantic cell (for a microbe) or is it a multi-cellular animal? Maybe we should ask Harold.

Vacuum on a Stalk

We looked at some green and white scum in Calvin's fish tank and we found that Calvin's fish, Harold, has lots of friends.

Below is a creature that appears to be a big vacuum mouth that sucks up particles. I don't know why it contracts violently all the time. Is that how it swallows its food?



Update: This appears to be a type of rotifer. These are multicellular animals with a mouth (called a corona, which makes me thirsty), primitive jaws (called trophi) and a stomach. They also have a foot and toes, which are sometimes attached to plants, as the example above appears to be.

Update #2:  It's a Vorticella. Thanks Mr. Comments!

Chlamydomonas with Flagella

Here is one of the little guys from the Christmas Germs post below where I wondered if they moved with a flagella or cilia. Here, at 1000x, we can actually see the flagella when it's not moving.



I believe this is a Chlamydomonas protozoan because it has a red eye spot and looks like these Chlamydomas species on Wikipedia.

Pin-tip

Here's the tip of a pin at 400x. It doesn't look very sharp, does it?

Monsters of the Shallows

We found these monsters (320 um long, or about a third of a millimeter, or 1/64th of an inch) in some scum from Lake Hodges.

They are paramecia, a type of protozoa. Here they are at various levels of magnification with some body parts identified.



Here are a bunch of them swimming around at 40x. You can also see some smaller creatures swimming around, but they are just tiny dots. Watch for one at the top by the pointer get stuck trying to squeeze through an opening that's too small.



Here they are at 100x. Here you can see the regular-size critters swimming around and you can see how big these monsters really are. This is also a good magnification to see the two contractile vacuoles which expel water. If it didn't have a way to pump out water, the little guys would explode!



Here's a movie at 400x. The monster is so big, we can't even see the whole thing at once at this level. We can also start to see the cilia moving and we get a pretty good view of its mouth.



This last one is at 1000x. This is actually the first movie I took, and at first I thought it was just an air bubble. And then I realized it was moving! You get a very close-up view of the water pumps and the mouth, plus little creatures get swept away from the monster's cilia. I also thought it was interesting to see how much stuff is going on inside the paramecium--it not just a bag of molecules.

Live & Active Cultures

I was about to have some yogurt as a snack when I noticed the "Live & Active Cultures" advertising on the side. Hmmmm, I wondered, and got out the microscope. I smeared some delicious Strawberry Breyers on a slide and then ate my snack--I wasn't sure I would still want to eat it after I looked at the slide.

Once I looked in the microscope, it was anti-climatic. It wasn't until 1000x that I saw some bacteria, and even then they are quite small, as you can see below. I'm pretty sure they are Streptococci thermophilis, because of all the bacteria they put in yogurt, these are the only ones which are spherical, whereas the others are rod-shaped.


None of the bacteria in yogurt are supposed to swim, but these little diplococci (double-berries) seemed to. However, they all "swam" in the same direction and are probably just flowing on some kind of micro-stream. The microscope lens pushed on the sample and it could have created a micro-flow. Here's a short movie showing them moving:



Why are bacteria in my yogurt? When these bacteria are added to milk, they feed on the lactose and make lactic acid as a by-product (see below). The acidity then curdles the milk proteins and also gives the final product--yogurt--its characteristic tangy flavor. Anyone else hungry for some delicious Live & Active Cultures?

Swimming Christmas Germs

We took a hike to Lake Hodges in San Diego County for a hike and picked up a few samples from the reservoir. The first I looked at was some green scum floating in one of our collection containers, and we found the creatures below.

It's funny that there are green and red variants--I didn't add any stains. The microscope is at 400x and the creatures are about 20 um in length (I finally calibrated the microscope). These appears to be protozoa rather than bacteria based on their size (bacteria are usually 0.5-5 um, protozoa are 10-50 um) and the appearance of internal structures which bacteria generally lack. (All this sound vaguely familiar from high school biology. I guess I should have paid better attention. Thank God for Wikipedia.)

In this first clip, a red and green creature hang out and spin around once in a while.



In the second clip, I chase after the green one to watch it swim. Sorry for the shaky camera work--I'm still getting used to moving the microscope stage.



Protozoa can be classified by their means of locomotion into the following four groups:

1. Flagellates - these move with one or more whip-like tails called ... wait for it ... flagella
2. Ciliates - pronounced silly-ates, these move with little hair-like thingies all around the cell
3. Amoeboids - these move around like The Blob
4. Sporozoans - they sound like something out of Scientology, but they are actually parasitic protozoa that don't have any means of locomotion

If you want to see examples of flagellates and ciliates swimming, check out this cool clip.

Since these guys swim, they must be either flagellates or ciliates. They spiral through the water when they swim, which seems like it would be the result of a whip-like tail rather than lots of little hairs. On the other hand, the Blepharisma is a ciliate and the Wikipedia entry notes that "It spirals as well as spins in a circular motion." I think I'll just name them Bob and Harold.

12-Legged Sand Crab

We found this little guy in the sand underneath the Oceanside pier. He's only about 1 mm long, and the movies below are at 40x. We've found other white sand crabs about an inch long (they're good for bait), and this might be a related species. However, it turns out to have 12 legs. Sand crabs belong to the order Decapoda, which means 10 feet. But this one has 12! Have we discovered a new order of crustacean, the Dodecapoda?



To get a better look at the legs, the crab was flipped over with a huge two-by-four (well, that's what it looked like under the microscope--in reality it was probably only the size of a tooth pick). At the beginning of this video, six legs can be clearly seen on one side. After a few minutes, this little guy figured out how to move by pushing his legs against the top of the drop of water. He's so smart!



I've been googling 12-legged crab and the only other creatures I've found are the horseshoe crab, and this unidentified greenie from CrustIDFAQs. Once again, it turns out it's easier to find interesting creatures than it is to identify them.

Our First Animal

We looked at the green scum in Calvin's jar and found nematode worms--our first multicellular animal! These movies were taken at 1000x with our oil immersion lens (there's a drop of oil between the lens and the slide to minimize optical distortion).

In this first clip, you can see the worm swimming through the water sucking up food particles. There are also other creatures that swim around, including the battle-ships seen previously. I'm now convinced they are swimming under their own power.



In the second clip, we trace the full length of the worm, from the head to the tail (at least I think it's a tail since I didn't see food particles going into it). It is 300 times longer than it is wide. If Calvin were that long, he'd be 230 feet tall! During this sequence, it's moving backwards--I wonder why.



The next clip shows our friend the nematode get stuck in some junk on the slide (I think it's from where I smeared the green scum on the glass). It's body doesn't seem to know that the tail is stuck and it just keeps pushing until the tail, just before seeming to break, springs around and frees itself.



In the last clip, our little fellow starts going forward again so we follow the nematode back to the head, where it runs into another nematode which isn't moving. Not only is there a battleship creature swimming nearby, several clear, quick-swimming creatures swim through the frame. One even gets stuck between the two nematodes, discovers its predicament, backs out, turns around and swims away. They seem to be smarter than the nematodes.



Who knew green scum was so interesting.