Agalma elegans has never been bred in a laboratory, because it is too fragile to keep in captivity.
Each animal produces male and female organs, the gonophores, and these mature at different times to prevent self-fertilisation. Eggs or sperm are released by different individuals, and fertilisation takes place externally in sea water.
One cormidium of the siphosome of Agalma elegans, showing the gastrozooid with a tentacle bearing many tentilla, palpons, bracts, and male and female reproductive organs. © Keith Hiscock (MBA, Plymouth)
The fertilised egg grows into a small siphonula larva which at first develops:
Gradually, as growth proceeds:
Finally, the animal matures and the lifecycle begins again.
The length of time taken to complete the lifecycle is unknown.