Last summer we had a rare event. Tens of black sea nettles (Chrysaora achlyos) washed ashore on our beach. These guys are pretty rare, so we jumped at the chance to get some gonadal tissue to start a new culture of jellies. We collected the adults from the beach, and I extracted the gonadal tissue from the insides of the bell. (This was a rather painful process which involved me getting stung for three days.)
I used bits of the tissue to sex the animals; females had eggs, and males had packets of sperm. After I figured out who was what, I put a little bit of male gonads and female gonads together in a petri dish and mixed them up, to beak open the male's sperm packets. (It felt a bit like making red scrambled eggs.)
Male sperm packets
Female tissue with eggs
After 3 days, planulae were spotted swimming in the petri dishes.
After 5 days, the planulae settled to the bottom to become polyps. These are newly settled with only 2 fully formed tentacles.
Four months later, I am very happy to say that my polyps have begun to strobilate. I have some beautiful ephyrea, that will become (in my opinion) the prettiest-colored jellies ever.