Nassula with ingested Cyanobacteria; & ejected Trichocys

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NikonUser
Posts: 2676
Joined: Thu Sep 04, 2008 2:03 am
Location: southern New Brunswick, Canada

Nassula with ingested Cyanobacteria; & ejected Trichocys

Post by NikonUser »

EDIT: title changed, was "In need of an Explanation"

Ecki showed an image of a cyanobacterium (cb) in the shell of a testate amoeba; apparentlty the cb was just an usurper.
HERE

Yesterday I saw what appeared to be a green circle racing around the bottom of my sample dish. On closer inspection it was seen to be a large ciliate with a coiled cb inside the ciliate's cell wall.
The ciliate is 360µ long; the cb much longer.
This raises several questions:
How did it get there?
Was it originally small and subsequently grew long in the ciliate?
Was it eaten?
Is it a parasite?
Any ideas for an ID of the ciliate?

Single frame with the ciliate besides an air bubble.
BHS DIC 20x SPlan Apo, 1.25x intermediate tube, 2.5x relay lens
Image
NUM10139
Last edited by NikonUser on Wed Dec 29, 2010 12:33 pm, edited 1 time in total.
NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.

Nikon camera, lenses and objectives
Olympus microscope and objectives

René
Posts: 467
Joined: Sun Oct 08, 2006 4:22 am

Post by René »

haha, nice image! It's a cyanobacteria filament and it's gobbled up via a small round mouth. I'm not entirely sure but I think you can find it at 2 o'clock in your image. If you search for Obertrumia (or Nassula), you'll see what I mean. They often occur together with cyano-blooms, sometimes even suggested for use as a natural predator.

Best wishes, Rene

BJ
Posts: 354
Joined: Sat Sep 29, 2007 10:53 am
Location: England

Post by BJ »

Hi NU,

some ciliates specialise in feeding on long filamentous cyanobacteria. The one I know a bit about is Nassula. You might imagine that it starts at one end of the filament and just keeps going, and sometimes I think that this is the case. However, the main method of attack is to grab the filament from the side. Nassula has a well developed "pharyngeal basket" made up of proteinaceous bars. When the ciliate grabs the filament, the basket twists and twists the filament into an "alpha" shape and then continues to ingest the filament as two parallel strands. The filament may then unravel again inside the ciliate, but is contained within a food vacuole.

So I think that is what you may be looking at.

regards
Brian

NikonUser
Posts: 2676
Joined: Thu Sep 04, 2008 2:03 am
Location: southern New Brunswick, Canada

Post by NikonUser »

Thanks Rene & Brian; I'm constantly amazed by the expertise here from you and others on PMG.net.
I would love to see this feeding behaviour in life; and yes I can see the mouth.
1 minute and 5 seconds after that image the ciliate began to disintegrate (slide probably drying out) and a whole batch of trichocysts were ejected from the rear end:
Image
NUM101040
NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.

Nikon camera, lenses and objectives
Olympus microscope and objectives

BJ
Posts: 354
Joined: Sat Sep 29, 2007 10:53 am
Location: England

Post by BJ »

NU,

wonderful photo - thank you!

Brian

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