What is this thing? Microbiology edition
October 30, 2017 10:11 AM Subscribe
I recently got a Foldscope and I'm a little obsessed with it. Last night I caught this critter on film. I would like to know what it is, and I'd also like information on where I can go on the web in the future to try and identify similar creatures.
(Yes, it looks like a wang.)
Details: It came from some pond water I collected a few days ago. I live in the Eastern US. This thing was large enough that it could actually be seen with a magnifying glass held up to the slide, so, pretty big. This image is at 140x and it was hanging out in a well (~2mm diameter) on a microwell slide.
(Yes, it looks like a wang.)
Details: It came from some pond water I collected a few days ago. I live in the Eastern US. This thing was large enough that it could actually be seen with a magnifying glass held up to the slide, so, pretty big. This image is at 140x and it was hanging out in a well (~2mm diameter) on a microwell slide.
I don’t think paramecia deform that much, also they use cilia to move, and I think we’d see them.
Given the rather deep invaginations and long thin tendrils it forms, as well as the clearly visible cytoplasmic flow, I’d say amoeba is more likely.
Here is a brief guide to Identifying freshwater microbes, here’s another.
posted by SaltySalticid at 11:46 AM on October 30, 2017 [2 favorites]
Given the rather deep invaginations and long thin tendrils it forms, as well as the clearly visible cytoplasmic flow, I’d say amoeba is more likely.
Here is a brief guide to Identifying freshwater microbes, here’s another.
posted by SaltySalticid at 11:46 AM on October 30, 2017 [2 favorites]
This page linked by Salty (go to Protozoa Portraits) shows an Aelosoma, which looks like your specimen.
posted by JimN2TAW at 12:39 PM on October 30, 2017 [2 favorites]
posted by JimN2TAW at 12:39 PM on October 30, 2017 [2 favorites]
Best answer: Well, let's break it down, shall we? What can we observe about it?
First, it has mobility; it lacks a rigid branching structure and chloroplasts. We can rule out most green/blue-green algae and organisms like diatoms. It lacks obvious flagella and obvious cilia, which means it's not one of the ciliates like a paramecium (in which case it would also be slipper shaped) or one of the flagellates like a dinoflagellate. Nor does it appear to have clear/obvious appendages, antennae, tentacles, so we can probably rule out a copepod, water flea, hydra, rotifer, tardigrade (water bear), or isopod. It is not shaped like a little clam, so it's not an ostracod. (Forgetting about size for now.)
It does not appear slipper shaped, barrel-shaped, or spherical. It has bilateral (or radial) symmetry with an anterior and posterior, with a clearly differentiated head and other segments, so it's not an amoeba or some of the other protozoans (in the stricter definition of the word). I It does appear to have bristles or filaments sticking out from its body from the middle of individual segments or rings; it's hard to get a good idea of its movement due to its restriction, but it does have control.
We know it's freshwater; we know it's less than 2mm but not much smaller. We know we're probably viewing it from an oblique angle, which might be possibly obscuring its size, true body structure, and tail, an important consideration. You know what depth and velocity of water you sampled from, which is information you can use to verify.
That narrows it down to larva or some kind of worm. It does not have tapered ends, so probably not a nematode. (In fact, thought I saw a nematode in there at one point.) It could be a flatworm, but it has segments. It could be a larva of some sort, but it's hard to verify that from the tail. With the size, segments, bristles, and distinguishable head, my best guess is some kind of annelid. There's a picture on this site that looks like your specimen. Note the rounded head with the indentation that you can clearly see in your video about 1:16. Here's a pic of a freshwater bristle worm and here's a video with two moving similarly. Another.
* * *
I don't have any great suggestions on IDing freshwater organisms but I do make my living identifying marine organisms on a microscope, and I can provide some suggestions there. I would start with two tools to help understand what you're seeing. One is understand even the most basic optics and microscopy. A short tutorial Nikkon's "Microscopy U", like the one on Field of View, even if it's not the same tool set, can help you understand how optics works in order to understand size and angles. (Nikkon also has a great pond life gallery here.) Understanding size is important for ID as you already intuitively understand from your question. You can pick and choose what would be useful from the list. Optics and sample prep - there probably was too much water in your sample; it's the little things like that can help.
Two, if you want to get better at identifying organisms, I'd get a basic notebook and draw them. You can pause a video like yours or start with something static, but try drawing what you're seeing. It's really basic, it doesn't have to be artistic or even good, but it helps train your eye to observe structures, and really helps with learning how to observe the details. Next thing you know, you'll want to learn what the structures are, then you'll learn more structures to observe because you're trying to differentiate, and you'll just get better at it, which in turn will help you with identification.
posted by barchan at 12:42 PM on October 30, 2017 [24 favorites]
First, it has mobility; it lacks a rigid branching structure and chloroplasts. We can rule out most green/blue-green algae and organisms like diatoms. It lacks obvious flagella and obvious cilia, which means it's not one of the ciliates like a paramecium (in which case it would also be slipper shaped) or one of the flagellates like a dinoflagellate. Nor does it appear to have clear/obvious appendages, antennae, tentacles, so we can probably rule out a copepod, water flea, hydra, rotifer, tardigrade (water bear), or isopod. It is not shaped like a little clam, so it's not an ostracod. (Forgetting about size for now.)
It does not appear slipper shaped, barrel-shaped, or spherical. It has bilateral (or radial) symmetry with an anterior and posterior, with a clearly differentiated head and other segments, so it's not an amoeba or some of the other protozoans (in the stricter definition of the word). I It does appear to have bristles or filaments sticking out from its body from the middle of individual segments or rings; it's hard to get a good idea of its movement due to its restriction, but it does have control.
We know it's freshwater; we know it's less than 2mm but not much smaller. We know we're probably viewing it from an oblique angle, which might be possibly obscuring its size, true body structure, and tail, an important consideration. You know what depth and velocity of water you sampled from, which is information you can use to verify.
That narrows it down to larva or some kind of worm. It does not have tapered ends, so probably not a nematode. (In fact, thought I saw a nematode in there at one point.) It could be a flatworm, but it has segments. It could be a larva of some sort, but it's hard to verify that from the tail. With the size, segments, bristles, and distinguishable head, my best guess is some kind of annelid. There's a picture on this site that looks like your specimen. Note the rounded head with the indentation that you can clearly see in your video about 1:16. Here's a pic of a freshwater bristle worm and here's a video with two moving similarly. Another.
* * *
I don't have any great suggestions on IDing freshwater organisms but I do make my living identifying marine organisms on a microscope, and I can provide some suggestions there. I would start with two tools to help understand what you're seeing. One is understand even the most basic optics and microscopy. A short tutorial Nikkon's "Microscopy U", like the one on Field of View, even if it's not the same tool set, can help you understand how optics works in order to understand size and angles. (Nikkon also has a great pond life gallery here.) Understanding size is important for ID as you already intuitively understand from your question. You can pick and choose what would be useful from the list. Optics and sample prep - there probably was too much water in your sample; it's the little things like that can help.
Two, if you want to get better at identifying organisms, I'd get a basic notebook and draw them. You can pause a video like yours or start with something static, but try drawing what you're seeing. It's really basic, it doesn't have to be artistic or even good, but it helps train your eye to observe structures, and really helps with learning how to observe the details. Next thing you know, you'll want to learn what the structures are, then you'll learn more structures to observe because you're trying to differentiate, and you'll just get better at it, which in turn will help you with identification.
posted by barchan at 12:42 PM on October 30, 2017 [24 favorites]
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posted by humboldt32 at 10:46 AM on October 30, 2017