For years now, we have been propagating mini maxi anemones. They are easy to propagate by cutting them in half and letting them heal for a month or two. Most aquacultured corals are asexually produced either by allowing them to split naturally or by propagation techniques such as cutting and remounting. It is very uncommon to see sexual reproduction.
Sexual reproduction in anemones is done by way of broadcast spawning, in which the anemones release both sperm and egg into the water column. Fertilized eggs later settle on the substrate and form new colonies. Coral and anemone spawning in home reef aquariums is not unheard of, but it is uncommon.
The main reason coral spawning is uncommon in most home aquariums is the close tie between spawning and the lunar cycles. Anemones rely so much on the moon for sexual reproduction that there is no guarantee an egg will come in contact with sperm. If they mistime their release of gametes by as little as 15 minutes, the chance of successful fertilization occurring is greatly minimized. Thus, they use the moon, sunset, and chemical receptors to determine the optimal time to spawn.
Most home aquariums do not simulate the phases of the moon (although some newer fixtures are incorporating this feature into their products). Here at the Tidal Gardens greenhouse, spawning does in fact occur. Recently, we observed our mini maxi carpet anemones spawning!
The other reason not too many people see spawning events is that most of the time, hobbyists aren’t looking at their tanks in the middle of the night. On this particular occasion, my friends and I decided to shoot some pictures at night.
While we were out there taking a look at the tanks, we came across one that was so cloudy that it was opaque. It was hard to see more than 6 inches into the aquarium. In comparison, the other tanks that are connected to the same system were crystal clear.
As with all our anemone tanks, we have a sponge filter on the drain line to prevent the anemones from jumping into the overflow. In this situation, it was keeping the sperm and eggs circulating in the 30-gallon tank and preventing them from getting flushed down into the rest of the system.
Hopefully, in a few weeks, we will see some signs of baby mini maxi anemones. Perhaps in the future, sexual reproduction of corals and anemones will be a sustainable method of propagation.