Please help ID these things

[Hawkdl2]

I happened to look at my tank tonight with a flashlight right after I turned out the lights and about 20 of these guys began swarming in the light. They wiggle and swim fairly rapidly. A few burrowed a little in the sand, but mostly they swam around and tried to stay in the light. They come in the smaller orange colored variety and the larger gray variety. The gray ones are about 3/8" and the orange ones are about 1/4".

Does anyone know what they are?

http://i12.photobucket.com/albums/a213/hawkdl2/90cubesquirmers.jpg

[PghFishNerd]

Ew they look so much like bristles, but I thought they just crawled as opposed to swimming. I'm not too sure on this one :(

[rssjsb]

Google epitoke. It's a free-swimming developmental stage of bristle worm.

[Hawkdl2]

I would not be surprised if they were, or are related to, bristle worms, but I've not been able to find a picture of an epitoke or bristle worm that looks like what I have. The orange ones do look a bit like peanut worms.

[mndfreeze]

You should net one and put it in a shallow dish for close up photo.

[Kataro]

I see this a few times also, and it does look like a bristle worm. I caught a blue / purple one along with some yellowish / tan / pink one

[Hawkdl2]

I didn't have time last night, but I plan on trying to capture a couple.

[LeslieH]

Those are definitely polychaete epitokes. Generally they have transparent skin so the color comes from the eggs or sperm within.