How to Distinguish from Similar Species: (The systematics and distribution of another species in the genus, O. carpenteri (Binney, 1860), are unclear)
Geographical Range: Alaska to San Luis Obispo county, California
Depth Range: Intertidal. This species spends considerable time above the water, especially in caves. This may be related to the fact that it has a lung instead of gills.
Habitat: Crevices, mussel beds, kelp holdfasts such as sea cabbage and Laminaria and red algae such as Odonthalia floccosa.
History: Often found
in as a group of several. Graze on diatoms from rocks and
low tide. On mechanical stimulation, the marginal tubercles
secretions that repel potential predators such as seastars, especially
hexactis, which retreats from an
nudus will eat dead individuals but not live
ones. Lays a
gelatinous mass of 6-40 encapsulated eggs. Hatch as young
Kozloff 1987, 1996
Smith and Carlton, 1975
General Notes and Observations: Locations, abundances, unusual behaviors:
Although Kozloff's key says this species is abundant throughout the region I have not noted it often except on the open coast. Perhaps this is because it is inconspicuous and usually found in caves, crevices, and holdfasts. In the summer of 2013, however, it was common along the north shore of Whidbey Island (see below).
Most years I have found this species only
in the summer of 2013 this species was very abundant on seaweed and
at North Beach and other beaches along the south margin of Deception
Whidbey Island, WA just south of our marine station. The
are several taken by my daughter, Joanna Cowles, at North Beach in the
summer of 2013.
Authors and Editors of Page:
Dave Cowles (2007): Created original page