Egregia menziesii is an exclusively marine brown alga commonly found on intertidal rocks in protected to moderately wave-exposed areas. It is mid-intertidal to subtidal (20m). The feather boa kelp can be found growing in mixed stands with Phyllospadix spp. (1)

E. menziesii consists of two geographically distributed populations based on morphology. The northern population is found from Alaska to Cape Mendicino, California. The southern population extends from Cape Mendicino to Baja, California(2). The southern population has a thinner, smoother rachis, wider blades, and tend to have blades attached to pneumatocysts.

There is a somewhat intermediate population found from the Channel Islands to Cape Mendocino vicinity and Ventura County and posses a combination of northern and southern features.