Need help to ID translucent critters

[jwc3]

Sorry, no photo, but here's a detailed description of the critters that are crawling on the glass of my tank:

They are small (about 4 to 5mm in length), color-less, translucent (see-through), and have a smooth body with a short a split tail. They are slow moving -- they lift up their front edge, stretch forward and flop down, then pull their back-end forward -- kind of a stretch/flop/slide process. They crawl on the glass, apparently eating algae. At first I thought they were some kind of nudibranch, but they have no color, no spikes, etc. and are very small.

I have about 10 of these things in my tank (that I can see) and they tend to congregate in the lower back corner in the shade. Perhaps that is a romantic spot where they like to make more?

Thanks for your help!

 

[Anonymous]

Really need a picture but it sounds like it could be a Harpacticoid Copepod:

mario

 

[jwc3]

Thanks, but no, that's not it. These things are like little slugs. More like a nudibranch. They have no legs, no eyes, no antenna, etc. Just a small clear/white blobs that move like a snail or slug. Also, these things are larger than a copepod -- about 1/4 inch long.

 

[Anonymous]

Sounds like a flatworm to me.

 

[Anonymous]

Look like these?

 

[jwc3]

Well, that's closer, but still not exactly what I have. My critters have very little color (the only color they have appears to be food inside their bodies), but the ones in the photo seem to have a yellow-ish tint. Also, all of the things in my tank are the same size, while the ones shown in the photo appear to be various sizes.

Since this doesn't seem to be an easy one to figure-out, I'll try to borrow a digital camera from work and post a photo soon.

 

[bhanson]

What about Stomatella

 

[jwc3]

Ah ha! I found a photo of one in the Hitchiker Photos topic. It's a White Flatwrom...

I assume they are harmelss??

Thanks for your help, everyone!

 

[jwc3]

OK, maybe you guys didn't see my last question. Are these White Flatworms harmless, or are the a pest that should be removed? Thanks.

 

[Anonymous]

They feed primarily on copepods and other small flatworms.
The problem with these animals is that they can multiply to plague like numbers and damage corals by shading them or cause toxic conditions in tanks by dying inmass.

Regards,
David Mohr

 

[Anonymous]

jwc,
What David is saying is, suck them ALL out. You do not want them in your tank.

 

[Mihai]

That does not match the advice I got on my white flatworm (or my experience for that matter):

http://www.reefs.org/phpBB2/viewtopic.php?t=53762

IME the white ones do not multiply like crazy - the brown/red ones are the bad type. I left them there, got like 20 of them and now I only see one every two-three weeks. This type is harmless IME.

I believe that the key difference is that the red ones are photosynthetic (just like the corals) and need little to thrive, while the white ones, once they finished off the copoepodes will starve and recede.

On the other hand David has far more knowledge than I do, so you may want to go with his advice (e.g. , it's possible that given the right conditions they may get out of hand).

M.