Field of Science

Marine Microforay – foram and a thecofilosean party

Apologies for disappearing for a while – had an interview, finals and then my arm decided to temporarily rediscover RSI-like symptoms just when I had a term paper to write, so I had to lay off extraneous typing for a while. Then I realised just how much of my life depends on typing, and losing that ability would not only make me worthless and unemployable, but also unable to communicate with many of my friends who happen to be inconveniently dispersed around the globe. So yeah, I should probably stop casually dismissing ergonomics about should you, if you haven't already!

I've accumulated another batch of microscopic findings, this time from marine samples. By the looks of it, I might be moving to the Midwest soon, and thus be deprived of my ocean (and mountains *sob*), so I figured that focusing on marine protists while I have the chance would be a good idea. Swampy pondwater is available pretty much anywhere anyway.

From time to time, you can be lucky enough to find a foram shell in the sediments around here. Live forams can be found too, but much more rarely – I have a couple, but still need to process the videos. This is not a snail:

Foram. Wreck Beach. 20x obj, DIC except for last image, which is in phase.

To save loading time, the rest are below the fold.

A pennate diatom of some sort, on its side. The girdle, where the two valves ('shells') meet, can be seen along the middle.

40x obj, DIC

A flagellate of some sort. Has a strange groove from which flagella appear to emerge (see bottom second from left). Looks like some sort of thecofilosean/cryomonad like Protaspis, but might be some heterotrophic euglenid for all I know.

A marine Thecamoeba-like thing: (as suggested by ridges on the surface)

The partial collar and flagellar pocket suggest euglenidness. Entosiphon sp, perhaps? Eats diatoms. Short flagella perplex me though; I vaguely recall having searched long and hard for their continuation, but they appeared truly short despite that.

And another individual, presumably of the same species or closely related.

This might be a cercomonad that ate something colourful and refractile. I recall it moved in a rather cercomonad-y fashion. Glides like hell.

An obvious thecofilosean. Verrucomonas or Protaspis; leaning towards Verrucomonas based on position of the massive nucleus (see top right) and how intensely the ventral groove bisects the cell; not sure how reliable those characters are. Looks like fig 1n in Chantangsi et al. 2010 Mol Phyl Evol, which is Verrucomonas longifila (also fig 1h and 3h in Chantangsi & Leander 2010 IJSEM). Can't say much else except that it's a gliding flagellate with a tendency to protrude fine pseudopodia from the groove along its bottom. Thecofiloseans aren't particularly overstudied or anything...

Another thecofilosean with colourful refractile inclusions – probably food-related (characteristic groove evident in rightmost image).

A Lecythium-like creature. Lecythium is a cercozoan organic-test-bearing amoeba with thin filose pseudopods. Plenty found in freshwater too.

A...thing. Appears to have colourful food vacuoles or something. In the top right image there's a barely visible groove edge of some sort along the right edge, with a kink too. Anyone offended if I write this off as a marine cercozoan, eg. cryomonad of some sort?

Metromonas simplex. It anchors to the substrate with the curly end of its flagellum and sways back and forth rhythmically, for hours on end. Back and forth, back and forth. Like a metronome, hence its name. Apparently it's got nothing better to do. Intend to upload some videos eventually... it's really cool! Uncertain affinity at this point, despite how quickly these guys are found everywhere after leaving some benthic seawater in a dish. Thinking I could quickly yoink a couple off the dish and PCR them to resolve the issue with little effort, I very quickly found out why no one's ever bothered and succeeded: these things are practically impossibly to pry off the surface! I think they've invented superglue or something...

Part of a decaying arthropod. Spherical things might be parasites/cysts, or some animal cell type I'm totally oblivious too. Wish there was an easy way to learn what the various cell types look like in arthropods – most introductory literature is tissue-oriented. I'm perplexed by the surface of the spherical things visible in the top right and bottom left images.

20x obj, DIC

The rest are from a different marine sample, captured by video camera.

This ciliate appears to be related to Paramecium based on the shape of its oral region, as well as the rectangular grid-like arrangement of the cortex. In the bottom middle image, the macronucleus is apparent as a clear-ish area in the cytoplasm. I think the top right features a contractile vacuole with its channel towards the left end.

Top two: 20x obj; bottom: 40x. DIC

Heterotrophic euglenid, or a cercozoan of some sort. Probably the former as there seem to be visible edges of pellicle strips in the top right image. The flagellar pocket also points towards a euglenid identity, though the flagella are a bit short and on the thin side. Could be out of focus though.

Discocelis saleuta, a common marine flagellate of uncertain affinity. The disc shape is very characteristic and cool, would probably make an interesting SEM subject. Apparently the cell edge can be lined with extrusomes (Vørs 1988 ref'd in Walker et al. 2011 Parasitol S1:88); given the flagellate is a mere 5µm, it's hard to imagine how those could even fit in there.

That was probably way too many images...


  1. Thank you for these images. I'm no biologist - I'm programmer, but I like your blog, because it helps me to get the basic intuitive insight into world of microorganisms (feels kind of like watching birds outside).

    I was wondering if you could sometime share some videos too. One of my favorite video is "Crawling Neutrophil Chasing a Bacterium" on youtube, it's fascinating. Unfortunately, there isn't much more like that.

  2. Thanks for sharing the neutrophil video – that was awesome!

    An intuitive feel is exactly what I've been trying to go for here, and I'm glad it works for someone. I'm not much of a logical abstract thinker myself, so I rely on intuition to find my way around, even in science.

    Anyway, you wish is being fulfilled: just started up a YouTube account: Will gradually fill it up with videos – I have tons! Though I don't really have the time to edit them at the moment, so I hope you don't mind raw footage for now...


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