Microscopy Thread

[EnterName]

Spirorbid Worm (Spirorbis sp.)​

Let me preface this by saying that I'm not really happy with the quality of today's post.
I have not yet set up my microscope for reflected light microscopy which makes larger specimens a challenge. I had to use dark-field and focus stacking and still didn't manage to get that nice crisp image I was looking for.

Common Name	Spirorbid Worm
Classification	Spirorbis sp.
Verdict	Beneficial
Size	≤ 1mm (0.04")
Found	Rockwork, Glass
Rarity	Common

This Spirorbid worm (see common hitchhiker guide section 3) was taken from my filter sump's glass wall:

(Spirorbis sp.)​

I still made an DIC recording so you can see what hides in the tiny little white spirals that you probably can find all over your tank. Again, it looks like Cthulhu's offspring just like post #24:

(Spirorbis sp. emerging from its shell)
​

 

[EnterName]

Unknown (Clathrina sp.?)​

Today I have taken some time to look at another sponge. These white "root-like" growths are found in many tanks sooner or later and sometimes cause some concerned questions here on Reef2Reef. It might belong to the genus Clathrina, but I'm not very sure about that. Either way, they are totally harmless filter feeders

(Sponge in filter sump)​

Common Name	Calcaerous Sponge
Classification	Unknown (possibly Clathrina sp.)
Verdict	Beneficial
Size	usually ≤ 10cm / 4"
Found	Rockwork, Filter sump
Rarity	Common

Under the microscope we can see the sponge's "Spicules" that are acting as its skeleton. In this case we are looking at "Triactines" (three-rayed spicules) that are calcium carbonate (CaCO₃) based. I was able to verify this by adding some acetic acid which slowly dissolved the spicules. Silicate based spicules would not have reacted.

(Calcareous Triactines and sponge tissue)​

I really love how they look when using polarized light. They suddenly appear colorized through a physical phenomenon known as Birefringence. You can also see sponge's cellular layer which is a whole rabbit hole in itself.

(Birefringence effect on spicules caused by polarized light)​

The beige ovals and small granular bits in the previous image are far more interesting than they might appear at first. After squishing the sample to spread the cells throughout the slide you can see that these cells have flagella and therefore can move quite a little bit on their own.

(Flagellated cells of the sponge)
​

Sponges have insane regenerative abilities which you can see live under the microscope. The cells will actively "find each other" and clump together again forming piles known as "aggregates" (you can see a few in the video already). Then they will start to form a new sponge where different cell types perform different tasks. I highly recommend reading a bit about Sponges and their regenerative capabilities, it's absolutely fascinating.

 

[EnterName]

Pineapple Sponge (Sycon sp.)​

Another day, another sponge! This time it's a Sycon sp. better known as Pineapple Sponge . They are absolutely harmless and even beneficial to your tank as you will see.

(Small Pineapple Sponge in sitting on the glass in my filter sump)
​

Common Name	Pineapple Sponge
Classification	Sycon sp.
Verdict	Beneficial
Size	≤ 5cm
Found	Rockwork, Filter sump
Rarity	Common

Microscopy Images/Videos​

Similar to the sponge I posted yesterday (Post #82) these sponges have calcareous spicules, but most of them are very long "spears" instead of three-rayed spicules.

(Long spear-like spicules on the outer layer of a Sycon sp.)​

A lot of debris is stuck in these spicules which makes sense considering that these sponges are filter feeders and clean your tank. In contrast to the sponge from yesterday they have a very obvious "Excurrent pore" where water exits the sponge once it's filtered. It's basically just a hole at the top of the sponge with another set of spear-like spicules:

(Excurrent pore "Osculum" of a Sycon sp.)
​

They have the same astonishing capability of fully regenerating from a few cells when injured. In the first section of the video down below you can see their cells wiggling around with flagella building cell-clusters ("aggregates") to form new sponges and recover.
As you have already seen this in my last post, I decided to focus mostly on what appears to be amoeba in between the sponge cells and a ciliate feeding on residues of a diatom found in the sponge's spicules.

 

[EnterName]

Unknown (Polychaete larvae?)​

I made a whole bunch of recordings today, but wasn't really satisfied with the quality. However, I stumbled upon this little fellow while searching through a detritus sample. I'm not sure what it is. I see some similarities to Post #12 but this one has visible bristles, and appears to possess some kind of masticatory system in its pharynx. The little tail at the end is another oddity.

(Unidentified specimen)​

I upgraded my posts in this thread a little bit to include a few details about the shown specimens. For this post these additional data points will remain empty until I have a proper identification.

Common Name	?
Classification	?
Verdict	?
Size	?
Found	Detritus
Rarity	?

 

[EnterName]

Acoel Flatworm (genus/species unknown)
Even though I have already posted a single image, I feel like these fellows deserve their own post.

(Flatworms sitting on the front glass of my reef tank)​

They remotely resemble Ghost flatworms (Amphiscolops sp.), but tend to have a darker coloration due to the zooxanthellae in their tissue which you can see further below. Actual ghost flatworms have no zooxanthellae.

I have millions of them in my tank and they have not caused any issues. I never see them on coral tissue, inverts, or fish making me believe they are more or less reef safe. I might still try to find an appropriate treatment to get rid of them, as they aren't too pleasant to look at and I suspect them of eating copepods.

Common Name	Flatworm
Classification	Order: Acoela (genus/species unknown)
Verdict	Neutral / Attention (don't confuse them with actually harmful flatworms)
Size	≤ 6mm (0.24")
Found	Glass, Rockwork
Rarity	Common, Pest-like (spreads aggressively once introduced)

The zooxanthellae become visible under the microscope when you get a specimen to hold still for a while or squish it a bit:

(Flatworm zooxanthellae)​

Even though these flatworms have zooxanthellae to profit from photosynthesis, I have seen them trying to eat an ostracod. The specimen spit out the ostracod after a while, but even trying it lets me believe they are mixotrophic. The mouth opening became clearly visible after spitting out the ostracod:

(Image from the post #1 showing the mouth opening very well)
​

It could be possible this specimen is another genus/species/strain, but I think the shape difference mostly comes from being a juvenile compared to the one I observed today:

(Flatworm swimming on slide + different body parts of a squished flatworm)​

At 0:32 you can see that the whole ventral (bottom) surface is covered in cilia for movement which makes those worms glide smoothly.

 

[sixty_reefer]

@EnterName have you come across this ones before?

 

[EnterName]

@EnterName have you come across this ones before?

I don't remember seeing a boat-shaped diatom in my tank. But I like them

Maybe it's some Navicula species?
I cannot see any Striae in the video which makes it more difficult to narrow down the genus, but I'm not an expert on diatoms anyway and probably won't be able to properly identify it.

 

[sixty_reefer]

Thank you for the direction mate, will do some more research on it, their population is growing fast and I’m only seeing them in the filament algae. it’s an odd behaviour it also seems that they are enough to make it go translucent.

 

[EnterName]

Thank you for the direction mate, will do some more research on it, their population is growing fast and I’m only seeing them in the filament algae. it’s an odd behaviour it also seems that they are enough to make it go translucent.

I regularly see diatoms attached to green algae. They like light just like green algae and can colonize the provided surface area. I have not heard of parasitic diatoms yet, so I assume they are

• shielding light off from the green filaments causing this part of the algae to lose color/chlorophyll, or
• they are accumulating near dead and decaying algae as the release of nutrients benefits them.

It might also be a mix of both. I frequently see them on detritus and even necrotic coral tissue after two corals stung each other. It depends on the tank though as the same job can be taken over by cyanobacteria.

 

[sixty_reefer]

I’m not sure to what

I regularly see diatoms attached to green algae. They like light just like green algae and can colonize the provided surface area. I have not heard of parasitic diatoms yet, so I assume they are

• shielding light off from the green filaments causing this part of the algae to lose color/chlorophyll, or
• they are accumulating near dead and decaying algae as the release of nutrients benefits them.

It might also be a mix of both. I frequently see them on detritus and even necrotic coral tissue after two corals stung each other. It depends on the tank though as the same job can be taken over by cyanobacteria.

method they are using but the microscopic world has definitely got me hooked up, I had no idea that something like this was even possible, will continue to monitor and see what happens. Thanks again for the help

 

[EnterName]

Diatoms (Unknown sp.)​

Adding new dry sand (Fiji White) to the system has significantly increased silicate levels and makes new diatom species appear that I've never seen in my tank before. You can clearly see them splitting apart to reproduce (a process called binary fission).

(Diatom cells at different stages of binary fission)
​

This particular species doesn't really work well with bright-field microscopy:

(Same diatom as above in bright-field)​

In contrast, other diatoms work just fine:

 

[EnterName]

Nematodes​

Nematodes have to be one of the most successful living beings on earth. They are literally everywhere, so it is of no surprise to find them in our reef tanks as well. They are basically very simple small worms. Some of them are parasitic, but if you see one digging through detritus or on algae samples you have most likely found a beneficial CUC member.

(Head/Anterior section of a nematode)

"In short, if all the matter in the universe except the nematodes were swept away, our world would still be dimly recognizable, and if, as disembodied spirits, we could then investigate it, we should find its mountains, hills, vales, rivers, lakes, and oceans represented by a film of nematodes." - Nathan Cobb
​

Common Name	Nematode
Classification	Phylum: Nematoda
Verdict	Harmless
Size	≤ 2.5mm (0.1")
Found	Everywhere
Rarity	Very common

(A large nematode wiggling between diatoms)

(Nematode in contaminated Nannochloropsis salina phytoplankton culture)

(Nematode in an air bubble on the microscope slide)​