Unusual Worm ID… not a common worm

[Brit’s Fish]

I broke down a 3 1/2 year old tank today and carefully inspected the rocks to make sure I didn’t miss anything I wanted to keep. I found this worm chilling on the underside of a rock that was home to a large patch of green hairy mushrooms. I know the rock was wild and TBH, I didn’t dip it because it also had some really cool feather dusters on it. I think it’s also been home to a very small mantis shrimp… I’ve heard clicking coming from the rock for the whole ~3 years I’ve had it.
Anyhow, all of the other rock in the tank was CaribSea LifeRock, so this guy had to come from this tiny 5”x2” rock with the mushrooms. I don’t think he ever did any damage but there was a little snail and hermit graveyard when I took the rock out. I’m blaming the possible mantis shrimp for that though.
This guy went to my LFS & they didn’t know exactly what it was either. Any thoughts?

 

[WalkerLovesTheOcean]

There's no picture attached.

 

[Brit’s Fish]

There's no picture attached.

I hadn’t finished typing but accidentally posted. Check now!

 

[ISpeakForTheSeas]

I broke down a 3 1/2 year old tank today and carefully inspected the rocks to make sure I didn’t miss anything I wanted to keep. I found this worm chilling on the underside of a rock that was home to a large patch of green hairy mushrooms. I know the rock was wild and TBH, I didn’t dip it because it also had some really cool feather dusters on it. I think it’s also been home to a very small mantis shrimp… I’ve heard clicking coming from the rock for the whole ~3 years I’ve had it.
Anyhow, all of the other rock in the tank was CaribSea LifeRock, so this guy had to come from this tiny 5”x2” rock with the mushrooms. I don’t think he ever did any damage but there was a little snail and hermit graveyard when I took the rock out. I’m blaming the possible mantis shrimp for that though.
This guy went to my LFS & they didn’t know exactly what it was either. Any thoughts?

Definitely a Scale Worm of some kind; my first thought would be a Lepidonotus species, but I'm not super familiar with scale worms at this point, so I'd have to verify that/figure out the species later (probably tomorrow).

Once I feel confident about the genus/species, I'll look into the diet if possible, but it's most likely predatory:

That's a kind of Polychaete (Bristle Worm) known as a Scale Worm (taxonomic suborder Aphroditiformia),

It's most likely predatory toward small inverts like pods, other bristleworms, micro brittle stars, bryozoans, foraminiferans, and possibly things like sponges, small shrimp or other small crustaceans, bivalves, etc. It'll probably also scavenge for food if given the chance.

So, not necessarily harmful in a tank, but not necessarily something you'd want to keep either.

 

[Brit’s Fish]

Definitely a Scale Worm of some kind; my first thought would be a Lepidonotus species, but I'm not super familiar with scale worms at this point, so I'd have to verify that/figure out the species later (probably tomorrow).

Once I feel confident about the genus/species, I'll look into the diet if possible, but it's most likely predatory:

Thank you! I had a feeling you’d know something. How did you gain all this knowledge of ocean critters?! I’ve learned a ton from you.
I’m going to do more reading on scale worms and the species you mentioned. It’s interesting that it survived in that tank for so long but there was a history of CUC eventually going missing. I wonder if it was eating scraps from the mantis shrimp, or whatever was clicking so loudly in that rock.
For reference, here’s the rock that the noises had been coming from and where I found this worm. The rock isn’t that big but there are tons of tunnels… any thoughts on what could be clicking in this specific rock so loudly that I can hear it across the room? Can mantis shrimp stay that small after a few years? I’m sure it’s this rock because minutes after I moved it from the old tank to the sump of the new tank, the clicking started in the new tank. Would love to find a mantis & have him show his little face. He could even have his own little tank, if I ever actually see him.

 

[WalkerLovesTheOcean]

How did you gain all this knowledge of ocean critters?!

I know right?! I wonder the same thing. Whoever is behind "ISpeakForTheSeas" (I love the name so much), is truly awesome!

 

[ISpeakForTheSeas]

Thank you! I had a feeling you’d know something. How did you gain all this knowledge of ocean critters?!

Haha, just a ton of reading and scouring the web for photos to compare with (preferably from scholarly sources).

any thoughts on what could be clicking in this specific rock so loudly that I can hear it across the room? Can mantis shrimp stay that small after a few years?

For clicking coming from inside a rock, mantis shrimp and pistol shrimp are about the things I can think of - yeah, some mantis shrimps species reportedly max out at ~4 cm or less (sometimes less than 1 cm), so some stay small enough forever.

 

[adamg77]

I second @ISpeakForTheSeas behind epic. Whenever I see a post like this I’m like yep I know who I’m tagging but you already answered

 

[Brit’s Fish]

Haha, just a ton of reading and scouring the web for photos to compare with (preferably from scholarly sources).

For clicking coming from inside a rock, mantis shrimp and pistol shrimp are about the things I can think of - yeah, some mantis shrimps species reportedly max out at ~4 cm or less (sometimes less than 1 cm), so some stay small enough forever.

Now that I’m down a rabbit hole, I found a website that sells scale worms from the tide pools in Maine and “Tidepool Tim” says that the ones they collect make clicking sounds too? Crazy. I’m sure they don’t click as loudly as what I’ve been hearing (I’m talking 30 feet away) but still interesting!

Scale Worms | Lepidonotus Squamatus | Gulf Of Maine, Inc.

Order Twelve-scaled Worms, one of the most common scale worms found on Maine's rocky shorelines. Lepidonotus Squamatus are perfect for ecological studies.

gulfofme.com

 

[F i s h y]

@ISpeakForTheSeas correct me if I'm wrong but you don't even have a tank up yet correct?

And I'll add the same sentiment... absolutely brilliant when it comes to IDs. Appreciate what you do around here.

 

[ISpeakForTheSeas]

Now that I’m down a rabbit hole, I found a website that sells scale worms from the tide pools in Maine and “Tidepool Tim” says that the ones they collect make clicking sounds too? Crazy. I’m sure they don’t click as loudly as what I’ve been hearing (I’m talking 30 feet away) but still interesting!

Scale Worms | Lepidonotus Squamatus | Gulf Of Maine, Inc.

Order Twelve-scaled Worms, one of the most common scale worms found on Maine's rocky shorelines. Lepidonotus Squamatus are perfect for ecological studies.

gulfofme.com

Cool! I'm familiar with the company, but I didn't read through that page/know scale worms could click - now I'm curious how loud they are and if it could be what you're hearing.

@ISpeakForTheSeas correct me if I'm wrong but you don't even have a tank up yet correct?

And I'll add the same sentiment... absolutely brilliant when it comes to IDs. Appreciate what you do around here.

Yeah, no tank yet - the landlords say no pets, and we still haven't found the right place to move into, so I'm still waiting (hopefully not waiting too much longer though, haha).

 

[Brit’s Fish]

Cool! I'm familiar with the company, but I didn't read through that page/know scale worms could click - now I'm curious how loud they are and if it could be what you're hearing.

Yeah, no tank yet - the landlords say no pets, and we still haven't found the right place to move into, so I'm still waiting (hopefully not waiting too much longer though, haha).

Holy moly! That’s even more impressive then. Talk about being prepared for anything!

 

[Brit’s Fish]

Cool! I'm familiar with the company, but I didn't read through that page/know scale worms could click - now I'm curious how loud they are and if it could be what you're hearing.

Yeah, no tank yet - the landlords say no pets, and we still haven't found the right place to move into, so I'm still waiting (hopefully not waiting too much longer though, haha).

I sent them an email to ask if they have any ideas on the volume of the clicking compared to a pistol shrimp snapping. I’ll update here if I hear anything! That website is also super cool.

 

[ISpeakForTheSeas]

Definitely a Scale Worm of some kind; my first thought would be a Lepidonotus species, but I'm not super familiar with scale worms at this point, so I'd have to verify that/figure out the species later (probably tomorrow).

Once I feel confident about the genus/species, I'll look into the diet if possible, but it's most likely predatory:

Good news and bad news - the good news is that the worm is definitely a scale worm from the family Polynoidae, and Lepidonotus is still the closest I know at the moment (L. clava in particular looks close but not quite right, and it's from colder water - it has been reported from the Red Sea and supposedly once from the Gulf of Mexico near South America, but I question both of those).

The bad news is that the Polynoidae family has ~175 currently recognized genera and would take forever to sort through, and the Lepidonotus genus is one of the most speciose (i.e. is one of the genera that contains the most species) in the family with several dozen recognized species.

This wouldn't be too bad, except a lot of the diagnostic criteria (the technical stuff to figure out the genus/species) require things like super close up microscope pics of the dorsal and ventral side bristles (the Notochaetae and Neurochaetae respectively), which are not generally readily obtained by hobbyists.

So, I'm content to say that it's either a Lepidonotus species or from the subfamily Lepidonotinae, and that it's most likely predatory as mentioned.