Reproduction & Embryology

Bryozoans reproduce by means of sexual and asexually reproduction. Another interesting thing about Bryozoans is that they have both ovaries and testes, in other words they are hermaphroditic. They have the best of both worlds.

Reproductions asexually occurs by budding off new zooids, which is the main way a colony grows in size. Also if a piece of a bryozoan was to break off, the piece can independently continue to grow and survive and form a new colony. This type of reproduction gives rise to colonies that composed entirely of clones of the first animal, called the ancestrula.

Another way of reproduction is by depositing both eggs and sperm directly into the water where they fuse. Yet some byrozoans brood their eggs within zooecium or special chamber called ovicells.


Embryology:

Following fertilization, larvae are produced which show wide variation in body form from species to species. The larvae of non-brooding bryozoans bryozoans feed during the larval stage, while the larvae of brooding bryozoans do not, since these larva tend to settle soon after release. the most common larval type in bryozoans is the cyphonautes larva which is somewhat triangular in shape and has an apical tuft of cilia. Upon settling, larvae attach via adhesive sacs and undergo metamorphosis to the adult form. The first zooid in a colony is called the ancestrula. It is from this individual that the rest of the colony will grow asexually from budding.





The cyphonautes larva. The most common larval form in bryozoa.






Another type of bryozoan larva from Bugula an arborescent type