What on earth is this?

[AwakenedReefer]

I noticed this guy swimming around the tank and his existence there I do not understand. Maybe somebody can clear it up for me.
It is very small about the size of a BB. It looks and swims like a jellyfish but as far as I know jellyfish have no business in this tank so I’m at a loss.

 

[madmarks]

I have no idea what this is but it is interesting you mention jellyfish. It looks a bit like the early medusa stage of a Box Jelly.

 

[AwakenedReefer]

I have no idea what this is but it is interesting you mention jellyfish. It looks a bit like the early medusa stage of a Box Jelly.

Wow, It really does. I wonder what the developmental time frame is. It just seems so unlikely.

 

[Ben.QLD2]

Do you use natural seawater? I do and sometimes have critters like this make their way into my tank. The most broad answer is that it's some sort of zooplanktonic organism.

 

[AwakenedReefer]

I do not use natural seawater. Also it’s a 4 month 7g with an hob filter and nano skimmer. Honestly it confuses me. I have half and interest to say it a ghost flat worm “blown up” being they are in the tank but I don’t know that is within their capability and it never flattened back out.

Last I added something to the tank was 3-4 weeks ago and it was 5 zoa frags from an aquaculture system in Utah. I did not dip.

Another interesting note, I did have an Emerald Crab spawn in the tank twice. Some time passed then one morning I noticed hundred of small pairs of eyes on the rocks.

Frankly I didn’t think things like this could survive the pumps, skimmers, ect. It’s fun to find these new things.

 

[ISpeakForTheSeas]

My understanding is that fry (like the emerald crab larvae) usually don't survive long (be it a result of starvation, predation, or mechanical removal), but sometimes you get a survivor or two. Medusas (like this one and some common hydroid species) seem to do pretty well regardless of mechanical removal though (they usually starve in our tanks is my understanding).

This specimen in question is definitely a medusa of something, but I'm not sure what. My guess would be a hydrozoan medusa though. As I understand it, most of the time these guys are short-lived in our tanks, though if it has adequate feed, it may survive for a long while.

 

[AwakenedReefer]

My understanding is that fry (like the emerald crab larvae) usually don't survive long (be it a result of starvation, predation, or mechanical removal), but sometimes you get a survivor or two. Medusas (like this one and some common hydroid species) seem to do pretty well regardless of mechanical removal though (they usually starve in our tanks is my understanding).

This specimen in question is definitely a medusa of something, but I'm not sure what. My guess would be a hydrozoan medusa though. As I understand it, most of the time these guys are short-lived in our tanks, though if it has adequate feed, it may survive for a long while.

Interesting thank you.