Worm question

[donya]

Hello everyone! For the very first time I just saw something rather Eunice-ish in one of my rocks, and I have no experience with this group of worms. It's too small for me to be able to easily count the tentacles, but the face looks right otherwise. It actually looks to me exactly like a photo I saw on another forum IDed by Leslie as an Onuphid worm, but I suppose that's not saying much given that I can't even count the tentacles.

Anyway, assuming my guess is right and there really are five tentacles on its head, there are some behaviors that seem to conflict with what I've read about the "bad" Eunicid worms:
- It's out and looking around with the lights on.
- It appeared to be having a snack on some Halimeda right before I sat down to type this.
- It doesn't get back into its home particularly fast when startled and pokes its head back out a few minutes later.

I'm guessing the reason I couldn't see it before is that there was a big bunch of dead Halimeda in front of its hole that I only just removed today. So far it hasn't come very far out of its burrow, just enough to snuffle around in the algae around the tunnel opening and chase off the occasional Amphipod. I haven't seen any damage to corals even though some were temporarily placed right in front of the tunnel until today.

I have read that not all Eunicids are a threat to standard livestock, and I do prefer to just leave worms where they are unless there is an actual risk of them harming my other animals or my hands. I would even say that this one has a cute face. Of course, if it turns out that the cute face is misleading and I do need to chase it out, I'm not too worried about that. The rocks are not stacked for the most part, there are only three of them that offer any sort of other tunnel this worm could slither into (the rest have big caves but no long skinny tunnels), and there is no piping or anything else for it to escape into. Still, I would rather avoid shooting soda into the rock and just let it eat algae if that's what it's going to keep doing.

Alright, getting to the actual question. My camera's macro ability isn't good enough to capture such a small worm clearly, as he is only a few mm in diameter and doesn't hold still, so behavior is all I've got right now. Is the behavior I've seen so far likely to be any indication of the worm's classification and/or future disposition if it grows?

Thanks in advance for any help.

 

[LeslieH]

If it's really an onuphid - which also has 5 head appendages - then it's likely to stay a herbivore as it grows. Eunicids are iffier to predict. Some are herbivores throughout life, some are predators, some are detritivores, some change feeding modes as they grow and some switch depending on what's available throughout their lives.

 

[donya]

Thanks Leslie!

Feeding time this afternoon got the worm's attention and it came much of the way out of its burrow for several minutes giving me a better look at it. Of course, it now looks to me much less like the picture I was looking at yesterday...I suppose I should have seen that coming lol.

I can say now that there are definitely five appendanges around the head, at least two of which are striped with alternating reddish brown and white/clear bands. What looks to be a couple of segments behind the head it also has a bright white band with two white projections, on on each side and very close to the center. The white band doesn't seem to wrap all the way around the worm, just over the dorsal side.

I occurs to me that even though I thought this was the first Eunicid or Eunicid relative I'd seen up close, I realize now that I totally forgot about some worms with very similar or perhaps the same features I had in a tank 3+ years back. At the time I never knew what they were, and they only got to about half the size of my current worm from what I saw, but they were omnivores and scavengers that never harmed anything. What's really been getting me about this worm is that light doesn't seem to bother it all, which was also true of the other worms I'm remembering.

I'll keep an eye on the worm and see if anything changes. On the plus side, if he's going to come out looking for munchies during the day, it won't be hard to keep track of him.

 

[LeslieH]

Good observations. That white band and the two cirri mean it's definitely an eunicid and a very high probability that it's in the genus Eunice.

It is interesting that it - and the others you had - is foraging during the day. My field experience is that reef species don't come out until night but maybe they can tell when a serial worm killer is in the neighborhood trying to catch them! :-D

 

[AJSTITAN14]

Ours comes out during the day if there's a bit of food within worm's reach.

On the other hand all construction work on the fortress is strictly done in the dark.

Our species selection for the tank excludes any species that might prey on worms so maybe you are right in that he feels safe enough to stick his head out during the day without any predators around.

 

[donya]

Thanks again Leslie!

Our species selection for the tank excludes any species that might prey on worms so maybe you are right in that he feels safe enough to stick his head out during the day without any predators around.

Hmm...are the predators pretty specific, or are Eunicids readily eaten by most animals that eat other polychaetes (crustaceans, aggressive fish, etc.)? There are three Dardanus megistos hermits in the tank that I would not want to run into if I was a small worm.

 

[AJSTITAN14]

Arrow crabs are worm killers and so are wrasses so we don't keep those.

Last year we brought home a really cute Chalk Bass who tried to eat our worm the 2nd day we had him so he went back to the LFS.

So, in my experience if it eats worms it eats Eunice worms. Not that we are taking any chances.

 

[donya]

So, in my experience if it eats worms it eats Eunice worms.

Oh dear...well, I guess what I've seen so far is pretty much what you say there. I have now seen a couple of the hermits and my female maroon clown have a go at Mr. worm, although none with any success. He's gotten away without problems so far with his ability to zip back so fast (finally got to see it!) but it looks like he may need to learn a bit of caution if he doesn't want to risk losing a feeler or two at some point.

I notice he has somewhat bricked up one of his less tight-fitting tunnel openings with debris and mucous and has added some bits of dead Halimeda around another opening.I presume it is the worm's doing at least, since I haven't seen anything else go in and out of those holes. Very interesting to watch the entrances develop; reminds me a bit of my mantis shrimp's masonry work (in another tank of course).

 

[LeslieH]

Eunice are burrowers and landscapers. I remember one short article which speculated that they're actually responsible for a lot of reef structure precisely because they do consolidate loose rocks & dead corals with their mucus. The inside of their burrows are lined with it. The ones that live in crevices or rock piles will have multiple entrances & branches. Ones that move into old sipunc, boring sponge, or clam tunnels in hard rock have to make due with however many openings already exist.

 

[AJSTITAN14]

Yes. ours is constantly working on his little fortress. If I leave a frag plug or something within a few inches of the rock it invariably gets dragged over. Just by luck our worm lives in a fist sized chunk of rock so to avoid him bothering anything else it was placed in the front corner of the tank away from the rest of the rock work.

 

[donya]

Eunice are burrowers and landscapers. I remember one short article which speculated that they're actually responsible for a lot of reef structure precisely because they do consolidate loose rocks & dead corals with their mucus. The inside of their burrows are lined with it. The ones that live in crevices or rock piles will have multiple entrances & branches. Ones that move into old sipunc, boring sponge, or clam tunnels in hard rock have to make due with however many openings already exist.

How cool! Mine's living in existing tunnels but has really gone to work making extended entryways out of whatever is lying around.

Yes. ours is constantly working on his little fortress. If I leave a frag plug or something within a few inches of the rock it invariably gets dragged over. Just by luck our worm lives in a fist sized chunk of rock so to avoid him bothering anything else it was placed in the front corner of the tank away from the rest of the rock work.

Do you have any pictures of yours? It must be quite big to drag frag plugs! Mine has a long way to go before he can be that ambitious.

Oh - there is also second worm in the tank now! At least I am pretty sure it is another Eunicid, although once again I didn't get a good tentacle count (not enough light by the burrow). Still, I actually thought my first worm had picked up and moved to the other side of the tank until I noticed that there is no white band on the new worm. This one has a sand bed tunnel along one of the rocks and is decorating the opening with some bits of stuff. It comes out periodically to gobble a bunch of sand grains with great enthusiasm and then dissappears. It is likely to be regurgitating the sand somewhere else, or actually getting some kind of microbial food from the grains?

 

[AJSTITAN14]

No, hes not that big. Maybe half a centimeter in diameter. He's just a beast when it comes to hauling rocks around. He's probably about a foot long. Ive drawn him out about 6 inches by tickling his tentacles with a piece of fish (with tweezers). This invariably draws the Nassarius and after I move the snail to the back of the tank a few times I get tired of it.

Ours eats sand too. Sand is covered in bacteria and microfauna from my understanding. Not to mention it probably has bits of detritus mixed in as well. We have seen the back end of the worm pop out of a hole and eject the sand. Our worm is also translucent in spots and we can see the sand pass through him as he swallows it which is kinda cool.

If you want to fool around with your worm be sure to consider his jaws. Any worm that can haul rocks around with his jaws is pretty strong and I have seen our worm bite a nassarius snail in a dispute over a piece of fish so hard that the snail panicked, did a barrel roll, turn 180 and fled as fast as possible.

We have tried photographing him but all we have are a bunch of blurry images with a green streak in the middle.