Anemone hiding under the rock? Fireworms?

[ariellemermaid]

I’m hoping someone can ID this from a video. I realize videos don’t seem to work well on iOS and the picture won’t do it justice. The creature is sessile, it’s been there a little while now although looks like it’s spread a bit. It looks like tiny filamentous strands with little balls at the tips. It’s under a rock ledge so it took up residence in a rather dark spot. Rock was dry rock years old now so it didn’t come in on that. My guess is some kind of anemone, hopefully not aiptasia (although if it is, it’s not ugly)….

On a related note, to the right of the picture is a bristle worm. This is the first time we’ve seen them in this invert coral QT tank. One is rather large, the one in the picture is fairly small. They’re not shy about coming out with the lights on. We’d like some guidance on when to consider removing them, how to know for sure if we’re dealing with fireworms, etc.

For context, this is a full 20gallon reef tank, just no fish, that we use to QT all inverts and corals from anywhere other than Tidal Gardens. It’s essentially an ULNS. The permanent corals are mostly weedy corals- we had a xenia forest that came and went, and now the Zoa family coral in the picture is taking over (we’re about to donate a bunch to Petco). However, I did just seed some of an encrusting SPS. So we care about the corals a little bit, but mostly the crabs, shrimp, snails, clams, and serpent starfish which is a permanent resident (and my favorite creature currently, he acts like an octopus!). Would bristle or fireworms pose much of a danger to these creatures?

 

[ISpeakForTheSeas]

The creature is sessile, it’s been there a little while now although looks like it’s spread a bit. It looks like tiny filamentous strands with little balls at the tips. It’s under a rock ledge so it took up residence in a rather dark spot. Rock was dry rock years old now so it didn’t come in on that. My guess is some kind of anemone, hopefully not aiptasia (although if it is, it’s not ugly)….

That's a Corallimorph (taxonomic family Corallimorphidae)/Ball Anemone - despite the name, they're actually related to (and could be considered to be a kind of) soft mushroom corals.

They're generally harmless, though some species can spread enough to cause issues.

On a related note, to the right of the picture is a bristle worm. This is the first time we’ve seen them in this invert coral QT tank. One is rather large, the one in the picture is fairly small. They’re not shy about coming out with the lights on. We’d like some guidance on when to consider removing them, how to know for sure if we’re dealing with fireworms, etc.

Based on the bristles of that worm on the right there, I'd guess it's some kind of Phyllodocid (a bristleworm from the taxonomic order Phyllodocida); worms from this order generally feed on pods, diatoms (sometimes other microalgae too), other small worms, mollusks (like very small clams and snails), and detritus.

In other words, Phyllodocid worms are generally going to be harmless/beneficial CUC members just like regular bristleworms.

Fireworms are bristleworms from the taxonomic family Amphinomidae; generally speaking (this is not a hard and fast rule by any means), these have clusters/tufts of white bristles rather than the typical little spikes with a single bristle sticking out (if that makes sense); they also frequently have red/orange, fluffy looking bunches of gills mixed in with the bristles. Some good examples to look at are Hermodice carunculata and Eurythoe complanata.

As mentioned, there are exemptions to these guidelines, and some of the other fireworms can look a lot more like regular bristleworms, but this should give you a decent, general ID guide.

The permanent corals are mostly weedy corals- we had a xenia forest that came and went, and now the Zoa family coral in the picture is taking over (we’re about to donate a bunch to Petco). However, I did just seed some of an encrusting SPS. So we care about the corals a little bit, but mostly the crabs, shrimp, snails, clams, and serpent starfish which is a permanent resident (and my favorite creature currently, he acts like an octopus!). Would bristle or fireworms pose much of a danger to these creatures?

Regular bristleworms should really only ever pose a threat to critters that are already on death's door, so if you see regular bristleworms eating something in your tank, that thing was probably already dead/nearly dead regardless. Fireworms are a slightly different story though.

Encrusting SPS, crabs, and serpent stars should (to my knowledge) be totally safe from fireworms.

Very small, soft-shelled crustaceans (like pods or very tiny shrimp), snails, and clams could all be at risk with fireworms, especially if they're not in great health/if they're dying.

I haven't heard of fireworms going after Zoanthids or Xenia, but it's possible that they might; when they go after corals, they tend to go after branching corals (Acros, Millies, Gorgs, etc.) and anemones rather than encrusting corals (the way their mouths work, encrusting species would likely be very, very difficult for them to eat). To my understanding, though, most fireworms prefer other foods over corals and nems, so they're generally harmless/beneficial, acting as CUC for your tank and basically eating whatever your fish don't unless you have too many of them in the tank/they're not getting enough food.

In other words, keep fireworms well fed and with their population under control, and they really shouldn't cause many issues for you.

 

[ariellemermaid]

This is the largest worm:

 

[ISpeakForTheSeas]

This is the largest worm:

I can't tell if those are tufts or "paddles" for the bristles. If they're tufts, then it's probably a fireworm; if they're paddles, then it's probably from the family Phyllodocidae (so it would be a Phyllodocid worm).