I have a few olive nerites (these are often kept as grazers in fresh water tanks) which lay eggs constantly.
(That one's shell is badly pitted from a previous life in a soft water tank.)
I've been fussing with the eggs for a few months now, and scouring the web for info about how to proceed. Most references to these snails say cryptic things like "Their life cycle is incredibly complicated" or "Breeding is nearly impossible." A few people in this forum seem to have some ideas about other nerite species, so I'm looking for suggestions.
When the snails lay eggs in fresh water, the eggs just sit there until I scrub them up or they erode away. I've moved several into a salt-water tank along with a plankton culture (tetraselmis sp.) and the eggs laid in that tank go through a few distinct phases:
That's a lousy picture, but you can see the different phases. New capsules are solid white -- after a week or so they become 'half full' -- solid white on one half and clear on the other -- later, there's nothing left but a ring on the glass. A few capsules turn dark and opaque on their way to the ring-on-glass phase.
My question (finally!) is: are these eggs hatching, or just dying and rotting as they did in fresh water? Does anyone know what nerite capsules look like as they develop or after they hatch? If I had nerite larvae floating around in my tank, would they be big enough to notice?
My understanding is that there will be several critical steps in rearing these guys:
1) Egg laying
2) Egg Hatching
3) Larval survival
4) Larval 'settling'
5) Metamorphosis into adult form
I have some ideas as to how to proceed with each phase. But first I need to know which one is the blocker. If there's anyone out there who could tell me more with better pictures, let me know and I'll dig out the microscope and get better egg close-ups.
Thanks!
