Stenolaemata, like bryozoans in general, reproduce both sexually and asexually. Sexually, most stenolaemata are her maphroditic. Different species may be simultaneous hermaphrodites, producing sperm and eggs at the same time, or protandric hermaphrodites, producing eggs and sperm at different times. Ovaries and testes form from modified auto-zooids. Most stenolaemata species temporarily keep their fertilized eggs within brood chambers modified from the coela of feeding zooids. Free-swimming sperm are snatched from open water by the autozooids and passed on to the eggs for fertilization.
The fertilized eggs undergo cleavage and become free-swimming larvae that force their way out of the brood chamber and become independent, free-swimming organisms. In a few days, they settle down on a growth-friendly substrate, each larva changing into a rootlike form, the ancestrula, which commences to grow asexually into an entire colony, building the skeleton and budding the zooids; the colony continues to grow in this fashion. If a piece of a colony is broken off from the rest, it can settle and build itself into a new, complete colony.
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