How to Distinguish from Similar Species:Nuttallia nuttallii lives farther south, in California and Baja California. The oval shape with extensive shiny periostracum and purple interior are unique to this clam in our area. Venerupis philippinarum, another introduced clam, may have a purple stain inside but the outer shell is sculptured with radial ridges and concentric growth lines, without shiny brown periostracum.
Geographical Range: Japan, British Columbia, San Juan Islands Area (Introduced from Japan)
Depth Range: High to mid intertidal
Habitat: In sand or sand/gravel, often in areas of freshwater seepage.
this genus live deeply buried (to 20 cm) in the sediment, resting on
right side with their long siphons extending to the surface.
are non-selective suspension feeders.
Dudas et al. (2005) found that the common local cancer crabs Metacarcinus magister (Dungeness crab) and Cancer productus (red rock crab) preferred the thin-shelled introduced varnish clam Nuttallia obscurata to the thicker-shelled clams Leukoma staminea and Venerupis philippinarum if access to all was equally easy. However, Nuttallia obscurata typically lives deeper in the sediment than do Leukoma staminea or Venerupis philippinarum. If they had to dig for them, Metacarcinus magister still ate more Nuttallia obscurata than it did of the other clam species, but C. productus' preference switched to Leukoma staminea and Venerupis philippinarum.
found in none of the local keys--is a recently introduced species
General Notes and Observations: Locations, abundances, unusual behaviors:
August 2006: A shell from this species was found on the beach in Bowman's Bay, within 1 km of the Rosario Marine Station.
2006-2007: A study by Lindsey Eggers around Whidbey Island revealed that this species is abundant at Long Point (east of Coupeville) and is present at Freeland beach and at Double Bluff.
Summer 2007: Another study by Lindsey Eggers found that very few of the Nuttallia obscurata at Long Point or Freeland contained any Pinnotherid crabs (0 crabs/48 clams at Long Point, 2 crabs/57 clams at Freeland). At Double Bluff, however, 51 Pinnotherid (pea) crabs were found in 51 Nuttallia obscurata clams. This is the highest rate of infestation by pea crabs reported for any species except for the pea crabs' definitive host, Tresus capax. The Pinnotherid crabs were not identified to species but most were Pinnixia, likely P. faba and P. littoralis. At least one crab appeared to be Fabia subquadrata.
Authors and Editors of Page:
Dave Cowles (2006): Created original page