Nerite Shell Pathology

[Brackishdude]

I recently ordered a group of olive nerites from arizona gardens, and several have shells that have lost the green coat in spots such that the white shell underneath is exposed, often looking worm-eaten (though this may just be the normal anatomy of the shell). A few have little or no green left.

Several questions:

Is this a common snail disorder?

Treatable/Terminal/Of-no-significance?

Are the apparently-unaffected snails doomed to the same fate?

Are my fish at risk?

Thanks

These guys are amazing. None seem worse for the wear despite the shell uglies, and every surface in the tank is polished.

 

[voo]

Sounds like it might be eroded due to acidic water, or maybe a lack of calcium in the water when growing. Not sure if it'll heal, but if you have alkaline water the shell should be ok.

 

[nmonks]

Voo is correct; this is shell dissolution.

Since a shell is not alive in any way (unlike a bone, which is alive) it cannot be repaired. Over time the pits in the water will fill up with algae and you won't notice them very much. It has no affect at all on the health of the snail.

Nerites are wonderful snails, and terribly overlooked and mistreated. They do need very hard water though, as you've discovered, and preferably some salt added.

Cheers,

Neale

 

[voo]

Since a shell is not alive in any way (unlike a bone, which is alive) it cannot be repaired.

Just curious, but if this is true then how does a shell grow as the snail grows?

 

[nmonks]

A very good question!

Snails (like all other molluscs) lay down the shell as they grow, secreting shell at the "opening" and working forwards. So the opening of the shell is always the bit most recently made. It's sort of similar to how we grow fingernails, which are produced at the base, but in themselves are not alive and don't get repaired: damage to the end of your nails is simply worn away as new nail pushes forwards.

So if you take a snail and snip off the end (this is easily done with Malayan livebearer snails) you'll see the snail doesn't repair the shell. It can't.

On the other hand, if you snip the opening of the shell, to a certain degree the snail can repair the damage by laying down a new layer of shell. But such repair can only be in the region immediately around the front, because that's where the shell-depositing tissue (known as the mantle) is located.

Cheers,

Neale

Just curious, but if this is true then how does a shell grow as the snail grows?

 

[voo]

Thanks for that, interesting stuff. Never knew any of that