Friends of Netarts Bay Watershed, Estuary, Beach, and Sea

Schizoporella sp.
Encrusting Bryozoan
Worldwide
Family Schizoporellidae
Native (maybe)

The Phylum Bryozoa (Moss Animals) take a diverse range of morphologies (body forms), but all are sessile colonies of zooids. Zooids are single animals that are part of a colony. Many of bryozoans we see along our coast are encrusting, that is they overlay a substrate surface with a thin spreading layer of zooids, whether that surface is a rock, another animal, or a seaweed. Each encrusting zooid has a non-living, calcified body wall (the zoecium which serves as an exoskeleton) and an underlying an epidermis. The wall is usually ornamented with bumps, spines, holes and other structures that are species specific, lending to identification. There is generally one large hole in the body wall (the orifice), sometimes covered by an operculum, through which the animal can extend its tentacled crown for feeding, breathing, and reproduction. Encrusting bryozoans are hermaphroditic.

The genus Schizoporella has many species worldwide. There are at least four on our coast, one of which is invasive from Japan, S. japonica, which is often colored orange and may be what is pictured here. These specimens were collected inside Netarts Bay near the boat ramp.

Membranipora membranacea
Kelp-Encrusting Bryozoan
Alaska to Mexico
Family Membraniporidae
Native or Non-native

This common bryozoan of, which there are two probable species in our area, grows on the blades of kelp, especially Nereocystis the Bull Kelp, but other algae as well. M. serrilamella is native, ranging from British Columbia to Southern California. M. membranacea, a European species, was introduced from the northeast Atlantic, maybe by way of the eastern Pacific. The one pictured here is the latter. While beachcombing, you may see colony patches that resemble silver crusts on kelp blades that have washed ashore. If the patches are large enough to intrude on neighboring colonies, they compete for space, either cooperatively or aggressively. When the kelp dies, so does the colony.

Encrusting bryozoans in the order Cheilostomata are generally considered colonies of connected zoids, each living in a calcified, box-like house called a zoecium. The zoids are suspension feeders that deploy a funnel-shaped tentacle crown called a lophophore, and each tentacle is equipped with rows of cilia that beat in concert to create currents which direct food to the mouth.

Bryozoans belong to a larger group called the Lophophorates that includes the phyla Bryozoa, Phorionida, and Brachiopoda. All members of this "clade" have a lophophore and an associated muscular flap that aids in capturing food, the epistome.

Membranipora is the primary food for a minute cryptic dorid nudibranch Corambe sp. (See Corambe steinbergerae in the section on mollusks.)

Membranipora membranacea

Extended lophophores

Unknown Encrusting Bryozoan

This encrusting cream-colored encrusts the vertical base of a large basalt rock, once known as wedding cake rock, at the north end of Tunnel Beach. The closest I can come to an identification is the genus Rhynchozoon sp., but that is a wild guess. If anyone knows this bryozoan, please email webspresident@aol.com.

Flustrellidra corniculata
Spiny Leather Bryozoan
Alaska to California
Family Flustrellididae
Native

Often mistaken for a seaweed, this Bryozoan, instead of being calcareous, has soft, leafy structure that looks very algae-like. It is a colony of interconnected animals (zooids), usually arranged in lobes, but sometimes encrusting, tan in color, with tiny branched "spines". It is found in the lower intertidal and sub-tidal zones of the the wave-swept rocky outer coast, usually associated with seaweeds. Each zooid feeds by extending a tentacled crown, the lophophore, into the water to capture suspended food particles. The tentacles are ciliated and create a current that directs food to the mouth. They reproduce both sexually and asexually by budding. Sextual reproduction results in a ciliated, free-swimming, triangular-shaped larva called a cyphonaute.

Zooids magnified

Sponsored by the Friends of Netarts Bay Watershed, Estuary, Beach and Sea (WEBS)