Unknown critter...ID help?

[mamagoose45]

Twice now we have seen these tiny little "critters" swimming in our tanks. Last night, we saw them for the second time, and saw three of them in the tank at once. They are a fleshy pink color, 1/4" at the maximum, and have no distinguishable head/tail ends - looks a lot like a wiggly pink piece of rice. The wiggling motion is what seems to propel them through the water.

The first time we saw one was probably 3 weeks ago, right after I had set up my 2.5 gallon nano. Last night we saw three of them in the 46 gallon bow. The one in the nano we saw with the lights on. Last night, we spotted them after the lights had gone out.

I know that I have given an incredibly scientific description (please note the sarcasm) but despite the fact that they seem very simple, they are suprisingly hard to describe. Brian took some pictures. If they turned out at all, we'll post them on here.

Does anyone have any idea what these little guys could be???

 

[kjbudsberg]

are they attracted to light?

 

[kjbudsberg]

are they attracted to light, and are they flat or round??

 

[KAiNE]

epitoke or bristleworm larvae.
Just my guess.

 

[mamagoose45]

Both times now that we've seen them, they've been mostly at the surface, so I would say yes on being attracted to light???

Bristleworm larvae would make sense because they are the same color as the mature bristleworms...

 

[DMBillies]

They do seem to hang at the surface, but not necessarily in the bleed over beams from my fuge light, so I'd say that they don't seem to be particularly attracted to light... but I haven't tried shining a flashlight or anything.

They are definitely round. I'd agree with the rice reference for their length, but are much skinnier.

The wiggling motion is incredibly fast and actually creates waves that move down the body of the thing (as in multiple crests and troughs that travel down it's body). Also, although they have no discernable head, they definitely always travel in the same direction (so one would assume that the forward end is their head).

I know that the pictures didn't come out because of the incredibly small size, speed with which they move, and crappy lighting. I did get some fuzzy videos (haven't actually looked at them yet) that are probably clear enough to show how they move, but I don't even know where to host them so that people can view them.

Kaine- I'll have to do some research to see if I can find a picture of either the epitoke or bristleworm larvae.

 

[DMBillies]

This discription sounds like it might be right although we haven't witnessed any bursting:
"Some bristleworms reproduce by epitoky: a portion of the bristleworm becomes packed with eggs or sperm and becomes highly specialised for swimming, some even developing eyes! This portion is called the epitoke. At mating time, the epitoke breaks off from the main worm and can move about on its own. Swimming to the surface, it is joined by the epitokes of other bristleworms. At the surface, the epitokes burst apart, releasing eggs and sperm for external fertilisation. In this way, the worms can reproduce without exposing the rest of their bodies to danger. However, while an epitoke might be a new segment produced by the animal, sometimes the entire animal is remodelled into an epitoke and rips itself apart during mating. Mating is usually triggered by the lunar cycle."

But this image doesn't look right:

The image even shows the flattened look that they are supposed to get to help them swim (as described by another site). Ours look totally round and smooth.

Pretty interesting stuff though... I learned my one thing for the day.

 

[KAiNE]

yea.. I had this discussion with Dr Ron about a year ago. I've got pictures somewhere, Ill try and dig them up tonight.
I have seen exactly what you are describing as well as larger ones (4-5") with a "head".
The ones with the "head" he called "epitokes" the others he said were probably bristleworm larvae, either way they were nothing to worry about.