Eutreptiella euglenid and Cylindrotheca sp. diatom [Edited]

pwnell · Post by **pwnell** » Thu Jan 03, 2013 7:16 pm

My initial post was to gather information. This is to show the Euglenoids and Closterium setaceum diatoms that live inside my reef aquarium, also in context.

First the closeup shots.

60x Objective, DIC

60x Objective, DIC, heavily cropped (see scale bar)

Then a shot for context - the green algae covering the inside glass panels in my reef aquarium consists of mostly Euglenoids, and about 5% diatoms. I never knew this, I thought the green algae was just that - some small filamentous algae.

Macro view of green algae covering the inside panels of my reef aquarium. Obviously the Euglenoids are of the saltwater variety.

BJ · Post by BJ » Fri Jan 04, 2013 1:16 pm

Hi Waldo,

with the close-up of the euglenoid flagellate it is easier to arrive at an ID. As the cell has more than one long flagellum, we can rule out Euglena (unless maybe in division). It looks to me as though one of the flagella is longer than the other and more "twisted". This will identify it as Eutreptiella sp. If the flagella were more or less the same length and both straight or bent (but neither twisted) it would be a Eutreptia sp.

In my experience, Euglena is rarely encountered in seawater and Eutreptiella is the most common.

Closterium setaceum is a freshwater desmid found in acidic bog pools and similar habitats. The shape is right, but with Closterium the chloroplasts are green. With golden brown chloroplasts your organism is a diatom as you say. It is either Cylindrotheca closterium or Nitzschia longissima. It is not possible to tell which one from your photo. However, given the environment (ie an aquarium) i would tend to Cylindrotheca - lets see what René thinks.

regards,
Brian

Mitch640 · Post by **Mitch640** » Fri Jan 04, 2013 1:35 pm

Beautiful images Waldo. I am also curious what made the marks on the glass?

pwnell · Post by **pwnell** » Fri Jan 04, 2013 1:40 pm

Here is a phase contrast image with a 40x objective. Does it help?

pwnell · Post by **pwnell** » Fri Jan 04, 2013 1:42 pm

Mitch640 wrote:Beautiful images Waldo. I am also curious what made the marks on the glass?

Thanks. On the left is Turbo snail marks where they had been eating away at the organisms. On the right is "kiss" marks as my lawnmower blenny scraped it off with his mouth. Lastly, in the middle is my efforts collecting a sample with a cotton swob.

BJ · Post by BJ » Sat Jan 05, 2013 10:18 am

Hi Waldo,

Sorry - my last reply was badly worded, when i said "It is not possible to tell which one from your photo." , it would have been better to say" it is not possible to say which one from a photo of live cells in water." You really need to look closely at the wall ("frustule") structure in a chemically cleaned prepared sample. So I am afraid your beautiful phase photo does not advance matters at all.

I see that Dominique replied to your other posting on this diatom. He and René are our two diatom experts. One of his suggested IDs is Nitzschia closterium - this is an alternative name for Cylindrotheca closterium.

regards,
Brian

pwnell · Post by **pwnell** » Sat Jan 05, 2013 10:52 am

Thank you for clearing that up. It makes sense as this is definitely a diatom in a (strong) saltwater environment, with an SG of 1.025.