Microscopic yellow and red worm? Critter ID please

[LilacBrandy]

Hello,

Can someone help me identify this critter. I've had an unhappy Hammer for a while so I decided to give it an iodine dip. I checked what was left in the dip water and found a couple of copepods but also several of these guys. This photo is at 10X - so they are about a quarter of the size of a copepod or even smaller. They have red bands like shrimp but aren't the same shape as a shrimp. They're uniform along the length and have about 35 legs on each side. There are four rounded feelers on its head.

 

[Peace River]

It may be polychaete worm larvae or new juvenile. If so, then not harmful. Hopefully others will chime in soon!

 

[LilacBrandy]

It may be polychaete worm larvae or new juvenile. If so, then not harmful. Hopefully others will chime in soon!

Thanks for replying, this is a great suggestion. Would love to know which species, the shrimp colouring is so prominent but it's definitely a polychaete like you mentioned.

 

[Peace River]

Thanks for replying, this is a great suggestion. Would love to know which species, the shrimp colouring is so prominent but it's definitely a polychaete like you mentioned.

It is most likely from the family Syllidae. Please know that the bright colors will likely fade as it matures.

 

[LilacBrandy]

It is most likely from the family Syllidae. Please know that the bright colors will likely fade as it matures.

Thank-you very much

 

[EnterName]

I'm confused... That looks like 100x magnification (10x objective and 10x ocular), which would make the specimen larger than copepods. Copepods are visible but quite hard to see with the naked eye due to being so small.

Did you mean amphipods by any chance? (see https://www.reef2reef.com/ams/guide-to-common-hitchhikers-in-reef-tanks.861/)

If that's 100x it could very well be a syllidae as was already said. I've never heard of something similar that is harmful. The harmful worms are usually large enough to observe pretty well without microscope.

 

[LilacBrandy]

I'm confused... That looks like 100x magnification (10x objective and 10x ocular), which would make the specimen larger than copepods. Copepods are visible but quite hard to see with the naked eye due to being so small.

Did you mean amphipods by any chance? (see https://www.reef2reef.com/ams/guide-to-common-hitchhikers-in-reef-tanks.861/)

If that's 100x it could very well be a syllidae as was already said. I've never heard of something similar that is harmful. The harmful worms are usually large enough to observe pretty well without microscope.

You're correct, it is 100x times and I'd been looking at copepods on the slide but I was using the 40x (so 400x) for them. Totally mixed up my magnifications. Thanks for clearing it up, these are in fact bigger than copepods, maybe double the size.

 

[EnterName]

I'm confused... That looks like 100x magnification (10x objective and 10x ocular), which would make the specimen larger than copepods. Copepods are visible but quite hard to see with the naked eye due to being so small.

Did you mean amphipods by any chance? (see https://www.reef2reef.com/ams/guide-to-common-hitchhikers-in-reef-tanks.861/)

If that's 100x it could very well be a syllidae as was already said. I've never heard of something similar that is harmful. The harmful worms are usually large enough to observe pretty well without microscope.

You're correct, it is 100x times and I'd been looking at copepods on the slide but I was using the 40x (so 400x) for them. Totally mixed up my magnifications. Thanks for clearing it up, these are in fact bigger than copepods, maybe double the size.

Glad I was able to clear things up a bit. It's just some polychaete and is very likely just cleaning up detritus. There are millions of these in pretty much every established tank even though species might differ.