Shell medium sized to large (to 159 mm: Hutsell et al., 1997), elongated, lightweight, arched, convex. Spire depressed to somewhat elevated, visible in ventral view. Holes medium sized, oval, elevated, usually 3-6 open. Dorsal surface irregular, with low and broad spiral cords and interstices as wide as cords, without fine spiral threads, intersected by growth lines forming occasional knobs. Coloration variable,
mottled and streaked with red, green, brown, and white. Between row of holes and columella, carina with knobs. Columella rather narrow. Nacre bright and light-colored, showing irregularities in dorsal surface. No muscle scar; occasionally with some crenulations in larger specimens.

Haliotis kamtschatkana (c.q. assimilis)

The shells which exhibit a 'northern morphology' have a more elongated overall shape, lighter weight, 3 to 6 open holes (tremata), exhibit a somewhat lumpy surface with prosocline ridges/folds emanating from the apex of the shell but not extending to the row of holes, and a spire that is more pronounced rather than flush with the suture. With respect to colors, some shells have a solid color but are generally orange or red. Most shells have some sort of patterning, usually a blotchy white or green, and uncommonly, a shell exhibits a spiral orange band and even more uncommonly a spiral green band. With respect to sculpture, most shells have ribs that are muted in height, sometimes without minor threads interspersed between major ribs, and sometimes with no discernable ribs or minor threads at all (smooth). The shell is generally much thinner and therefore more lightweight than the 'southern morphology' forms. Though some shells exhibit some very prominent prosocline ridges about the apex, others can exhibit almost no undulations but are still thin. There is usually a fairly deep channel in the peripheral area between the row of holes and the columella.

The shells which exhibit a 'southern morphology' have a more rounded overall shape, medium weight, 4 to 7 open holes (tremata), exhibit a fairly smooth surface with raised and/or colored spiral ribs, and a spire that is more flush with the suture. With respect to colors, some shells have a solid color (orange, red, green, and rarely white), some have variable colored ribs that resemble porcupine quills, some exhibit pinwheel color patterns, and about 5 to 10% of the population exhibit a spiral orange band. Rarely, this spiral band is red or green rather than orange. With respect to sculpture, most shells exhibit raised ribs and usually there are 10 to 16 wider ribs with sets of 3 to 4 minor threads in between the major ribs. The shell surface can range from nearly smooth to somewhat lumpy (having prosocline ridges/folds) in a small percentage of specimens. The shell is generally thicker and therefore more medium in weight than the 'northern morphology' specimens. Some southern shells are extremely deep, resembling hemispheres. There is a groove between the row of holes and the columella but not as pronounced as the deeper channel found in the specimens exhibiting more northern morphology.

The animal appears similar throughout the range with the only variable being the intensity of color particularly around the outer margin of the foot (which is a more intense orange in northern populations). Epipodial characteristics are commonly used to delineate abalone species, however there are no observable differences throughout northern or southern populations of the animal. This is true of the radulae as well (Geiger & Owen, 2012).

Haliotis kamtschatkana assimilis: Shell large (to 184 mm: Hutsell et al., 1997), somewhat oblong, arched, convex, light to medium weight. Spire hardly elevated, hardly visible in ventral view. Holes medium sized, round to oblong, somewhat elevated, usually 4-7 open. Dorsal surface with distinct spiral cords of variable width and spacing, some low and broad radial folds. Color mottled and streaked; green, red, brown, and white; occasionally with orange spiral band. Columella rather narrow. Nacre bright with green and blue sheen. No muscle scar; occasionally with crenulations.

It has been demonstrated that shells exhibiting both 'southern' and 'northern' morphology are observed throughout the species distribution from at least southern Oregon, USA, to its southern-most point in central Baja California, Mexico. The Alaska, USA, population consists predominantly of shells which exhibit the 'northern' morphology and share marked similarity to shells found in Canada and Washington, USA. Both southern and northern looking shells exhibit the spiral orange band but the propensity for this to occur varies from roughly 10% in the southernmost range to almost 0% in the northernmost range. Intermediate specimens of the 'northern' and 'southern' morphologies are found throughout the entire range as well. In conclusion, Haliotis kamtschatkana is a single highly polymorphic and color variant species that exhibits most variability in its southern range and significant but less variability in the northernmost range.

Haliotis kamtschatkana assimilis from central and southern California is rounder, more convex, somewhat heavier, and has somewhat more prominent spiral sculpture. Haliotis walallensis from Washington to California is flatter and more flared, has finer spiral sculpture, and smaller, less elevated holes. Haliotis discus from Japan has a lower shell and regular low and broad spiral cords with fine spiral threads in the interstices

Haliotis kamtschatkana assimilis: Haliotis k. kamtschatkana found from Alaska to Washington is more elongated, less convex, somewhat more lightweight, and with less prominent spiral sculpture. Haliotis rufescens from central Oregon to southern California is heavier, less convex, lacks the strong spiral cording, and has irregular prosocline folds. Haliotis sorenseni from southern California to Baja California is more convex to inflated, does not have the strong cording but only fine spiral threads, has much more raised holes, and is lighter colored.

Type locality: Oonalaszka Island, Kamchatka. By original designation.
Range: Alaska to Point Conception, central California. The species exhibits isothermal submergence: In its northern range it is found in shallow water, whereas in the southern end it inhabits depths from 12-18 m, exceptionally to 100 m, along exposed to semi-exposed coasts. In shallow water it is found in cracks and crevices, but ventures out to the open rock in deeper water. The species feeds on small algae (Cox, 1962; Sloan &Breen, 1988).

Haliotis kamtschatkana assimilis: Type locality: Monterey; San Diego, California. By original designation.
Range: Central to southern California and central Baja California