(photos of Neil McDaniel, Canada: specimens from British Columbia)
This is a member of recently described genus Urtibrina. It closely resembles Urticina but differs in some internal features and molecularly.
Specimens of Urtibrina rimicola attach to rocky substrates, usually with the pedal disc inserted tightly into a crack or crevice in the rocky bottom and with only the oral disc with the tentacles visible on the surface. When expanded the oral disc does not stand proud of the bottom, instead it spreads out near the surface of the substrate. The species was observed from the low intertidal and shallow subtidal zones to a depth of at least 5 metres. In general, it appears to be an open-coast species, found along the outer rocky shores. It appears to thrive in surge or wave-swept habitats. Known only from the North East Pacific, and currently known to occur from Cape Flattery, Washington State, USA north to the west coast of Graham Island, Haida Gwaii, British Columbia, Canada. There have been many sightings along the west coast of Vancouver Island (in Barkley Sound and Quatsino Sound, British Columbia, Canada).
A similar (or possibly partially conspecific) species along the Pacific coast of the USA and Canada is often misidentified as Urticina coriacea. This name is invalid being a junior synonym of Urticina felina, a species restricted to European waters and not present in the Pacific.
