Macoma carlottensis Whiteaves, 1880 is abundant (up to approximately 350 nr2) in subtidal infaunal communities on the continental shelf of western United States (Lie & Kelly, 1970; Word, 1979) and in British Columbia fjords (Ellis, 1969). Of thirteen different species of Macoma identified from the coastal waters of southern British Columbia, M. carlottensis is the most tolerant to variations in water depth, sediment particle size, current exposure, and salinity (Dunnill & Ellis, 1969). Observations of the species maintained in sediment trays in our laboratory suggest thatM. carlottensis is an infaunal, primarily sub-surface deposit feeder which generally lies at a depth of 1-4 cm with its left valve downwards. Filter feeding was observed in some instances as indicated by extension of the siphons from 0-5-3 cm above the substrate.