Small worm

[stAlphonzo]

I am currently cycling my new tank. I started it with 50 lbs of dry rock, but got a 2 lb piece for the bacteria and coralline. The piece of live rock has been in the tank since 9/27/2018. This evening I happened to see a worm swimming around which I would like to ID. I managed to get one picture of it but now it's gone again. Since I'm cycling the tank, my ammonia, nitrite and nitrate are a bit high, so I really wonder if it would live anyway, but it seems to have managed to survive this long. Anyway, anyone know what this thing is and whether I should keep it or try to catch it?

If the picture stinks, I will try to get another if it comes out again.

 

[Dsnakes]

Does it look like it has hairs on it? The color looks like a bristle worm.

 

[Heavymman]

I am currently cycling my new tank. I started it with 50 lbs of dry rock, but got a 2 lb piece for the bacteria and coralline. The piece of live rock has been in the tank since 9/27/2018. This evening I happened to see a worm swimming around which I would like to ID. I managed to get one picture of it but now it's gone again. Since I'm cycling the tank, my ammonia, nitrite and nitrate are a bit high, so I really wonder if it would live anyway, but it seems to have managed to survive this long. Anyway, anyone know what this thing is and whether I should keep it or try to catch it?

If the picture stinks, I will try to get another if it comes out again.

Peanut worm?

 

[stAlphonzo]

Does it look like it has hairs on it? The color looks like a bristle worm.

It doesn't appear to have any hair on it. It is very small, about an inch long so possibly a juvenile. I assume that means it can change color and form, etc, but for now no hair. It really looks like a small, skinny earthworm.

 

[stAlphonzo]

Peanut worm?

I considered peanut worm. It looked a bit like the picture in Crab's sticky, but much smaller and thinner.

 

[stAlphonzo]

The one thing that might be unique and help ID this thing is its swimming pattern. When I saw it swimming around in the main water column, the front would twitch around pretty frantically to drive it. The back part appeared to just follow along for the ride. It was a really odd thing. I wish I had taken a video instead of stills. Either way, it's disappeared again but not sure if it found a nook in the rock or one of the many little spots in the sand.

 

[stAlphonzo]

Ok, so I did see someone on another forum suggest that the swimming pattern I saw is characteristic of epitokes from eunicid worms. I am not sure what that means yet.

Here is a terrible picture which shows the shape while it swims.

 

[stAlphonzo]

I also found another thread with a similar looking worm where Crabs suggested Dorvilleidae .

It did look a little like a small version of this without the noticeable hairs ...



I guess at this point, without a true positive ID, I will just proceed onward. I still have a ways to go on the cycle and when I get some CUC in there, I will wait and watch for anything to mysteriously disappear.

 

[stAlphonzo]

Finally the thing came out again so I caught it and took a video. It is still hard to really see the features of the worm, but hopefully it is more useful and someone can help me ID this thing. Also, it's been in the bowl for about an hour and I see this saliva like slime that it left behind.

 

[Joshua2598]

Bristle worm epitoke?

 

[stAlphonzo]

Epitoke looks right from what I've seen, plus in the glass bowl, I can see that it's segmented.

So, here is a follow up question since I've only just heard this word today.

1. If it's epitoke, we know it's a Polychaeta, right?
2. But we don't really know whether it's a good Polychaeta, like what everyone here calls bristleworm or a bad one, like the bobbit worm or fireworm?
3. Is there a good way to tell at this stage?
4. If it's an epitoke it won't really grow into an adult worm anyway, right? My naive understanding is that they need to lay or fertilize eggs which hatch and form into larvae/juvenile/adult stages. After the eggs are laid and fertilized, the epitoke die, right?

That saliva looking slime must be eggs or sperm then.

I'm inclined to let it go back into the tank but I really wish I had a sump set up at the moment. Thoughts?