Gastropods

Click on photo to enlarge. Scale line in photo equals 1cm unless otherwise specified.
* Species which are commonly encountered on the beach.

Lacuna variegata Carpenter, 1864
Variegated Lacuna *
intertidal to shallow subtidal size to 16mm
northern Mexico to central Alaska
This 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.

Lacuna vincta (Montagu, 1803)
Northern Lacuna *
intertidal to subtidal size to 16mm
California to northern Alaska; circumpolar
This 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)

Littorina scutulata Gould, 1849
Checkered Periwinkle *
intertidal northern Mexico to northern Alaska size to 19mm
This 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.

Littorina sitkana Philippi, 1846
Sitka Periwinkle *
intertidal southern Oregon to northern Alaska; Japan; Siberia size to 25mm
This 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.

Littorina subrotundata (Carpenter, 1864)
Salt Marsh Periwinkle
high intertidal northern California to southern BC size to 8mm
This 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
intertidal to shallow subtidal California to BC, maybe Alaska size to at least 10mm
This 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.

Family Littorinidae