Gastropods

Nassariidae

Yachats, OR Freshwater Bay, WA, subtidal Monterey, CA, subtidal Ucluelet, BC

Caesia fossata (Gould, 1850)
Giant Western Nassa
intertidal to 18m northern Mexico to southern Alaska size to 50mm
This is sometimes found intertidally. The shell has a beaded sculpture and may be orangish-tan to gray-brown. The rim of the aperture is usually orange. It prefers a mud/silt habitat.
(previous names - Nassarius fossatus, Nassa fossata, Alectrion fossatus)

Centennial Beach, Boundary Bay, BC Centennial Beach, Boundary Bay, BC, intertidal

Nassarius fraterculus (Dunker, 1860)
Japanese Nassa
intertidal northern Washington to southern BC; Japan size to 15mm
This is an introduced species from Japan and is occasionally found in the areas where it was introduced. It is similar to our native H. mendica. This has slightly angled axial ribs and faint spiral grooves.
There may be light colored stripes on the shell and the aperture is usually yellowish with dark stripes.
(previous name - Hima fratercula, Nassa fraterculus)

Crescent Beach, Boundary Bay, BC Crescent Beach, Boundary Bay, BC, intertidal Willapa Bay, WA, intertidal

Ilyanassa obsoleta (Say, 1822)
Black Dog Whelk
intertidal to shallow subtidal central California to southern BC; Florida to southeast Canada size to 30mm
This species was introduced from the east coast of North America. It can be very common where it is introduced. The shell is gray to black with a glossy black aperture. The shell is often weathered looking. The snails prefer a muddy habitat.
(previous names - Tritia obsoleta, Nassarius obsoletus, Alectrion obsoleta, Desmondia obsoleta)

Silverdale, WA Birch Bay, WA, intertidal

Nassarius mendicus (Gould, 1849)
Western Lean Nassa *
intertidal to 75m northern Mexico to northern Alaska size to 22mm
This is commonly found intertidally. The shell is usually gray to brown but may also be striped with white. It has spiral cords and straight axial ribs which can give it a somewhat beaded appearance. These may also be worn down to muted sculpture. The Nassa snails are scavengers.
(synonyms - Hima mendica, Alectrion mendicus, Nassarius cooperi, Nassarius indisputabilus)

Harfordia harfordii (Stearns, 1871)
Harford's Spindle
subtidal size to 52mm
northern California to BC
This shell has spiral ridges and a thick periostracum. The live animal is bright orange.

Olividae

off Neah Bay, WA West Seattle, WA, subtidal

Callianax baetica (Carpenter, 1864)
Baetic Olive
intertidal to 60m northern Mexico to northern Alaska size to 27mm
This is rarely found intertidally in our area. The shell is variably colored in shades of brown and is frequently patterned with zig-zag lines or splotches. The shoulders usually have darker lines and the shell is glossy. It prefers a muddy to silty habitat and is often buried in the sediment. A recent paper suggests this should be called Callianax alectona (Duclos, 1835) but as the paper indicates that C. alectona may be a complex of species, we will await further study.
(synonyms - Olivella baetica, Olivella diegensis, Olivella mexicana, Olivella porteri, Olivella pedrona)

Callianax strigata (Reeve, 1850)
Zigzag Olive
intertidal to 46m southern California to northern BC size to 15mm
This is very infrequently found north of Oregon. It is more squat than the Baetic Olive. This one is also distinguished by its distinct wavy lines on a pale background. The shell is glossy.
(synonyms - Callianax pycna, Olivella pycna)

Callianax biplicata (Sowerby, 1825)
Purple Olive *
intertidal to 50m northern Mexico to southern Alaska size to 35mm
This is commonly found intertidally in some areas, usually open coastal beaches. The shell may be brown to purplish in color with the occasional white or yellowish one found. The aperture and bottom fold are white. The shell width can vary for its height. At low tide look for raised trails in the sand to find this species. The coastal native peoples commonly used olives for necklaces and decoration and it is still highly regarded by the Makah Nation in Washington.
(synonyms - Olivella biplicata, Olivella angelana, Olivella lapillus, Olivella fucana, Olivella parva)

Family Nassariidae, Fasciolariidae

& Olividae