Click on photo to enlarge. Scale line in photo equals 1cm unless otherwise specified.
* Species which are commonly encountered on the beach.
Marrowstone Island, WA
eggs, Bainbridge Is., WA, subtidal
perhaps being eaten by the Margarite
Lacuna variegata Carpenter, 1864
Variegated Lacuna *
intertidal to shallow subtidal size to 16mm
northern Mexico to central Alaska
is somewhat common to find. It lives on eelgrass and algaes.
The typical size found is less than 5mm. It usually
has brown chevron markings on the shell. It lays small, rounded, "buttons"
of egg clusters, which are yellow.
Birch Bay State Park, WA, intertidal
Lacuna vincta (Montagu, 1803)
Northern Lacuna *
to subtidal size to 16mm
northern Alaska; circumpolar
is very common intertidally. The typical size found averages 5mm.
It is commonly much larger in the more northern part of its
range. It can be found on eelgrass, kelp and other marine plants.
The shell often exhibits white bands, but this may also be
absent. It lays small, donut-shaped egg clusters which are yellow.
(previous names - Epheria vincta, Lacuna carinata)
Bremerton, WA, intertidal (possibly L. plena) Littorina scutulata Gould, 1849Checkered Periwinkle * intertidal northern Mexico to northern Alaska size to 19mm
is extremely common to find. It can be very abundant in the mid
to high intertidal zone. The shell may be a solid color from
brown to black, or marked with a checkered pattern. The shell may
be smooth or have very fine spiral lines . The animal is
dark with speckled antennae. Another species, Littorina plena, overlaps the range and habitat of L. scutulata.
Their appearance is very similar also. They can be
determined via dissection. Some of our photos may actually be L. plena. See a detailed description on asnailsodyssey.com.
This page last revised: 12-19-2021
Nanaimo, BC, intertidal
Littorina sitkana Philippi, 1846
Sitka Periwinkle *
southern Oregon to northern Alaska;
Japan; Siberia size to 25mm
is a common species to find in the mid to high intertidal zone.
The shell is squat with a wide aperture. It may be smooth or have obvious spiral grooves. The color is variable from white to orange to black or variably striped. The animal is dark in color, as are the antennae.
Nanaimo, BC, intertidal
Littorina subrotundata (Carpenter, 1864)
Salt Marsh Periwinkle
intertidal northern California to
southern BC size to 8mm
small species is found in the very high intertidal or in the salt marsh
above the beach. It is more commonly found in the southern part
of its range. The shell is light brown to
black and may be striped. The shell is thinner than our other
two periwinkles. The antennae are light in color and may have some dark markings. The similar L. sitkana have darker antennae and can grow much larger in size.
(synonyms - Algamorda subrotundata, Littorina newcombiana)
Whiskey Creek Beach, WA
Neah Bay, WA, intertidal
Lacuna porrecta Carpenter, 1864
to shallow subtidal California to BC,
maybe Alaska size to at least
is infrequently found. It prefers the outer coast and only
inhabits the west portion of the Strait of Juan de Fuca in the
Salish Sea. The yellow egg clusters are similar to the donut-shape of L. vincta, but are larger, with a larger center hole.