"Doesn't mean you can't raise anemones from broadcast spawning. You just need to be ready for them - similar to how you need to be prepared for spawning clowns. Whereas people have been raising clowns successfully for 20 years now, you still wouldn't expect to have any baby clowns miraculously survive in your main tank after a spawn."
Good way to put it. I wonder what conditions would need to be provided for broadcast spawning anemones to successfully be bred so the larvae could grow out before becoming polyps?
I posted this in another thread I referenced above, but I'll copy it again here. Most of this is based on my experience with raising coral larvae, but I have raised Northwest Pacific anemones (two species of Urticina sp.).
Well, there are a couple of options. Typically with broadcast spawning species, sperm concentration matters - not enough sperm and you won't get good fertilization; too much sperm and you risk polyspermy (more than one spem fertilizing an egg = death of the larvae). And guess what, it's species specific, at least with corals. Again, I've never worked with your species of anemone, so you might need to look through some literature, if there is any...??? With that disclaimer...
Obviously, you want to mix like with like - and it seems as if you have several species of the same, so your chances of having boys and girls is good. If you can catch them in the act (like it looks like you did), I would move each anemone (if you can) to an individual tank/bucket (like 2.5 gallon tanks). Limiting the amount of water they are in is key, b/c it is easier to dilute sperm concentration than increase it - just add water. If females start releasing eggs, you'll need to start pipetting out the eggs and moving them to the other anemone's sperm in the other tank/bucket - now you are doing specific crosses. Even better, is to pipette out sperm and eggs and hold them in a small, clear cup - or even a 50 mL vial. Most likely, proper sperm concentration is going to have the appearance of lemonade.
At least in corals (and assuming sperm concentration is optimal), fertilization can/will happen within an hour. If you want to leave the eggs in for two hours, probably okay. If you went this route, then you need to be sure to rinse the eggs. When that sperm starts dying off, it will foul the water and kill your larvae. Gently pipette out the eggs and transfer them to clean water, remembering to keep the species separate. Don't forget to put your adults back in the display...
But, what if you come home and they have all already started smokin' their cigs...? Well, now you just have to hope that nature can take it's course in your tank. You probably have overflows which means much of the spawn has found it's way to your sump and is gone. If you have any left, shut off all you pumps/powerheads and wait. I know it's hard watching all that stuff pollute your tank, but give it at least an hour if you can. I'm sure you can occupy your time mixing up new water for a water change, etc. If the eggs are positively buoyant, it will be easiest to get them out just by using a cup to skim them off the surface. If they are neutrally or negatively buoyant, then you'll need to pipette or use a baster to get them out. Whatever you do, BE GENTLE! Most developing larvae are very delicate for the first day or so, and you can tear the membranes very easily. Unfertilized eggs will typically crumble apart in 24 hours, maybe less.
So, lets's say you now are fortunate enough to have fertilized eggs - what in the heck are you going to do with them? Again, you have options. The least amount of work will be to create a holding tank/cup/bucket/whatever plastic basin you can come up with (really, a kreisel is easiest), with some micron mesh glued on holes you have cut/drilled in the sides - small enough that the eggs can't fit through, so it doesn't have to be 10 micron or anything. 100 micron would probably be fine. Basically, this keeps you from having to do water changes. Add in VERY GENTLE air bubbling for the first day at least. If the developing larvae cram together, they can fuse, probably resulting in their death. The other option is to just float a small tank, say gallon or so, in your display and change the water once a day. You should add the gentle air bubbler here too and try to keep the eggs from binding and clumping together. After the first 24 hours, you can increase the vigor of the bubbling, just don't bash them around. You can also gently stir the eggs to separate them. I recommend stirring every 1/2 hour to hour or so. You are in for a long night.
Now, you wait. Access to a low-power dissecting scope is a REALLY big help, b/c you can see cell division start to happen within the first few hours - it's amazingly fast - then blastula, gastrulation, etc., etc. It's really very cool. With this, you can keep tabs on how the larvae are developing and take pictures through the occular to document growth. Eventually, they will become ciliated, start swimming and want to settle, and here the story can really get species specific. I have no idea what the settlement cues for your anemones are, so again consult the literature. They might not require much more than a biofilm, and I've had anemones settle on the tank glass.
Then... you have to get them zooxanthellae. It's possible the parent might donate some to the egg, but if not you can 1) hope they take some up from the water column or 2) take a snip from an adult, grind it up and release it into your settlement tank.
Ideally, if you get settlement, you'll have a dedicated grow-out tank for the larvae. I would not put them in an established reef, though you could plumb that tank into your existing reef to help with water quality.
Now, assuming you have settlers and they have metamorphosed, they are going to be hungry. Start with feeding them anything meaty and small - newly-hatched brine is nice, rotifers (frozen or live), probably cyclopeez - ya know, tiny, plankton-sized.
Of course, the above is mostly based on my experience with corals, but I did have two different species of Pacific Northwest anemones spawn back in May 2010, and I did both the methods I described above, and it worked. I have juveniles of both species growing. Yes, it was an exhausting week.
Brooders are infinitely easier to work with. Never underestimate the power of settlement-competent larvae... :rollface:
Cheers
Mike