Super tiny... hydroid?

[Michael Hughes]

It was not easy to get a shot of this little thing with my phone. The central disc, for lack of a better term, is somewhere around half a millimeter (estimate).

@EnterName have you seen something like this before?

 

[EnterName]

It's a bit too irregular for a Hydroid medusa, I suppose or can it swim away and looks like a jelly fish?
https://www.reef2reef.com/threads/microscopy-thread.1138845/post-14401843

Hydroids can create the oddest structures: https://www.reef2reef.com/threads/microscopy-thread.1138845/post-14463276
So maybe it's just the beginning of some colony

 

[Michael Hughes]

It's a bit too irregular for a Hydroid medusa, I suppose or can it swim away and looks like a jelly fish?
https://www.reef2reef.com/threads/microscopy-thread.1138845/post-14401843

Hydroids can create the oddest structures: https://www.reef2reef.com/threads/microscopy-thread.1138845/post-14463276
So maybe it's just the beginning of some colony

I haven't seem them swim to my knowledge. First noticed them in my pico tank a few months ago after adding some macroalgae, oyster shells, and hermits from the Atlantic coast of FL.

Over a few months they mostly disappeared from the acrylic. I later transferred some stuff from that tank to the 125 g. That was about a month ago, and this is the first time I've seen one on the glass here. It wasn't there yesterday though, so perhaps it could be a recently settled/attached medusa?

 

[EnterName]

It's a bit too irregular for a Hydroid medusa, I suppose or can it swim away and looks like a jelly fish?
https://www.reef2reef.com/threads/microscopy-thread.1138845/post-14401843

Hydroids can create the oddest structures: https://www.reef2reef.com/threads/microscopy-thread.1138845/post-14463276
So maybe it's just the beginning of some colony

I haven't seem them swim to my knowledge. First noticed them in my pico tank a few months ago after adding some macroalgae, oyster shells, and hermits from the Atlantic coast of FL.

Over a few months they mostly disappeared from the acrylic. I later transferred some stuff from that tank to the 125 g. That was about a month ago, and this is the first time I've seen one on the glass here. It wasn't there yesterday though, so perhaps it could be a recently settled/attached medusa?

You should be able to use a pipette to get it out and have a closer look.

These things can be really odd. I had medusoids and "digitate hydroids" (the tentacles) when the system was less than a year old. Then they disappeared completely. After I transferred the rocks, water, and livestock into a new tank (same size as the old one), they showed up again for a while.

I don't know why they disappear after a while or where they come from in the first place, but they don't seem to cause any long-term issues.

Maybe the biofilm that builds up on all surfaces over time is unfavorable for them, and that's why new tanks work better. Or maybe something eats them or filters out their eggs/spores, like sponges that first need to establish themselves in the sump or plumbing before they become effective.

Fascinating creatures, as long as they don't cause trouble, I kind of like them

 

[Michael Hughes]

You should be able to use a pipette to get it out and have a closer look.

These things can be really odd. I had medusoids and "digitate hydroids" (the tentacles) when the system was less than a year old. Then they disappeared completely. After I transferred the rocks, water, and livestock into a new tank (same size as the old one), they showed up again for a while.

I don't know why they disappear after a while or where they come from in the first place, but they don't seem to cause any long-term issues.

Maybe the biofilm that builds up on all surfaces over time is unfavorable for them, and that's why new tanks work better. Or maybe something eats them or filters out their eggs/spores, like sponges that first need to establish themselves in the sump or plumbing before they become effective.

Fascinating creatures, as long as they don't cause trouble, I kind of like them

Still tough to photograph, but they are suddenly all over my macroalgae. I'll guess I'll just keep an eye on them and see what happens.

 

[Michael Hughes]

You should be able to use a pipette to get it out and have a closer look.

If I remember tomorrow I'll see if I can pipette some out to throw under a scope at work.

 

[EnterName]

Still tough to photograph, but they are suddenly all over my macroalgae. I'll guess I'll just keep an eye on them and see what happens.

I assume there's something growing or living on that macroalgae that makes it a good spot to settle. For now, I would just enjoy having some cute little "substitute jellyfish" in your tank

If I remember tomorrow I'll see if I can pipette some out to throw under a scope at work.

I would be very interested in seeing some images or videos. I'm wondering if yours differ from those I have recorded.

 

[Michael Hughes]

 

[Michael Hughes]

Terrible chromatic aberration, but at least it shows the movement.

 

[Michael Hughes]

This thing appears to have asexually fragmented itself while on the slide. No wonder they're spreading so fast

 

[EnterName]

So they are indeed different from the medusoids I have found in my tank! Really really cool. I would love to have one or two of them to take a closer look. Maybe I get lucky when I set up a test tank for some experiments

 

[Michael Hughes]

So they are indeed different from the medusoids I have found in my tank! Really really cool. I would love to have one or two of them to take a closer look. Maybe I get lucky when I set up a test tank for some experiments

As best as I can tell, these are probably in the suborder Capitata. The nematocyst-filled knobs at the end of the tentacles are pretty pronounced.

Hopefully you'll get a chance to see some of your own!

 

[EnterName]

So they are indeed different from the medusoids I have found in my tank! Really really cool. I would love to have one or two of them to take a closer look. Maybe I get lucky when I set up a test tank for some experiments

As best as I can tell, these are probably in the suborder Capitata. The nematocyst-filled knobs at the end of the tentacles are pretty pronounced.

Hopefully you'll get a chance to see some of your own!

If your guess is capitata then maybe some of them will grow into these weird things: https://www.reef2reef.com/threads/microscopy-thread.1138845/post-14463276

I'm not sure if the knobs are only an identifying feature in "grown" specimen, yours might still be partially a medusoid it's very motile still.

You are obviously welcome to share your recordings in the linked thread as well