Bryozoans

Bryozoans

Bryozoans are colonial animals of uncertain evolutionary descent. They may be related to freshwater rotifers. Bryozoans are found in the lower intertidal to subtidal zones, attached to a firm substrate, and also in brackish water. Individual animals are too small to see with the naked eye.

Bryozoan growth forms range from encrusting, forming coatings on hard surfaces, to bushy. An entire colony may bear a superficial resemblance to a hydroid colony, although bryozoans are internally more advanced than cnidarians. Bryozoan colonies grow to 3", and are occasionally larger.

Bryozoan anatomy
Note separate mouth and anus, unlike hydroid
Spiral Tufted Byozoans
Spiral Tufted Byozoans Amanthia spp

Hydroids

Masses of hydroids adorn many of the offshore wrecks, mixed in with anemones, sponges, mussels, coral, and algae. Hydroids are the most primitive Cnidarians, closely related to Hydromedusae, and display the most even split between the sessile polyp stages and free-swimming medusa stages, which are quite small and common.

The common Pink-Hearted Hydroid Tubularia spp generally grows in rounded tufts up to 6" across. Siphonophores are free-living hydroids that are often highly venomous, although most attached forms are harmless to humans.