Predatory snails

[SDguy]

Just wanted your opinions on these snails, and what I should do. They don't looks like sundial snails, but they are cleary predatory since they are found in/around my zoas, and those zoas aren't looking so hot. They have a tiger stripe appearance. What do you guys think about them, and what should I do? Obviously manual extraction works to an extent, but is that enough? With a 30" tall tank, even if I can see the snail, I can't always reach it easily. By the time may hand is in the right location, I can no longer see the snail from my angle of vision. Interesting hat they also seem to hang around my clams....coincidence? Multi food source predators? My clams look fine though...

I've included a pic of one on my zoas, for size reference...

 

[zolovinglover]

Those snails are harmless, and the zoas look pretty good to me. Color is virbant, polyps are extended, plump, and healthy.

 

[SRT80]

looks like collonista snails to me...

Steve

 

[SDguy]

Really? Huh...

Well, your ID seems correct after a search. Thanks!

And now that I'm looking around the tank, I agree, all my zoas look fine, except these:

What's weird is I have two colonies of these, in completely different area of the tank, totally different lighting, etc. Both look ill. The other one looks much worse than this one. Most polyps were expelling a brown substance (zooxanthellae?) this morning.

This is what they used to look like:

 

[zolovinglover]

From the looks of those zoas, they require somewhat large particles of food. What do you feed and how often?

 

[SDguy]

I never feed any of my zoas. They were all fine, spreading, until just these, about a month ago. Just looking less plump. Some with body columns curved or bent. Some with their centers cone shaped, with the mouth sticking up at a point, and skirts almost non existent.

 

[650-IS350]

Do the look like there reaching for more light ????

 

[SDguy]

One of the two colonies is up high. It looks worse than the one that is down low (which is pictured above - yes, they are longer than the ones up high).