"spider web" looking covering

[jona74]

Was doing a PWC and noticed that my entire substrate is carpeted by a thin layer of what I can best describe as looking like "spider web" looking strings. I just noticed them since the lower level of water in my tank during my PWC has caused some stronger flow near the bottom and I can see the strings waving freely from the substrate. My tank is 3 months old, and I have diatoms on glass and substrate as well. The bloom has decreased somewhat over the last few weeks, and I am of the understanding that the diatom bloom is a normal process of a new tank. You can see the strings on the substrate in the pic as well as on the darker shell in the middle of the pic. I just added a sand sifting sea star 3 days ago, but I am unsure if the stringy things were there prior. Any info on this would be appreciated

 

[mr_X]

That looks to be a vermetid snail. It will release those web-like strands to catch food. They never move and once attached to something, they sort of toss out a net for food.

 

[jona74]

Would this snail be able to carpet my entire substrate? Would these types of snails be a common hitchhiker since I have not purchased any? Also the shells in the pic were supposed to be empty since I got them from my LFS. I asked them about purchasing some empty ones just for aesthetics and they gave me a whole bunch of them for free. Would they normally be in tells, or on live rock. Thanks for the previous reply BTW

 

[mr_X]

If there were enough of them, yes, it would look like the substrate was covered. In the picture, the thing in the dead center looks like a vermetid snail opening. Uncover that and see what you have there.

 

[jona74]

took out the shell and nothing was in it. I have about 10 or so shells on the substrate so I guess they could be in any of them... just for my information, if you know, what are they trying to catch? what is their diet? and if they do "catch" something, how do they reach it if they are stationary? thanks again!!

 

[mr_X]

Vermetid snails catch whatever is in the water column. Not fish or anything you are worried about, but particulate matter. they are somewhat of a nuisance, but not because they eat your livestock, just for the webs. I'm still talking about the thing in the foreground of the pic, not the astrea snail shell.

 

[jona74]

yes it was an upside down nerite snail shell.

 

[mr_X]

Oh..then I don't know what is going on. Maybe a few more pics.