Description: This Cheilostome bryozoan forms a thick, encrusting colony. The zooecia are more complex than simple calcified tubes. The aperture of each zooecium has an operculum. At least 3/4 of the frontal portion is calcified, so that there are no obvious pores on the frontal portion. Moderate-sized avicularia can be found mounted on a mound (umbo) on the frontal of each zooid on the edge of the aperture, but they are not on the midline of the zooid frontal. The rostrum and mandible of the avicularium, though it is spaced quite close to the aperture, do not hang over the aperture. The mandible of the avicularium is spatulate. The zooids have no cardelles but do have a lyrula. The frontal has prominent ribs running from the margins to the umbo.
How to Distinguish from Similar Species: Rhamphostomella cellata has a small avicularium that fits into the rim of the peristome. Several other Rhamphostomella species have an avicularium that overhangs the aperture.
Geographical Range: North Pacific and Arctic Oceans including Kodiak, Alaska, the coastline of Russia, and Svalbard Island north of Norway.
Habitat: (It is uncommon to find this bryozoan encrusting a scallop, as this one was)
History: This species
incubates a few large eggs at a time within a brood chamber (Ostrovsky
et al., 2009).
Kozloff, 1987, 1996
General Notes and Observations: Locations, abundances, unusual behaviors:
Authors and Editors
Salish Sea Invertebrates web site provided courtesy of Walla