Class: Gastropoda,
Family Muricidae
Family type species: Nucella lapillus (Linnaeus, 1758) An Atlantic species

The common west coast gastropod Nucella lamellosa (Gmelin, 1791), common name: Frilled Dogwinkle, is the most variable species to be studied. In the 9 years that I have been seriously collecting and studying this species, I have found a few answers to my questions but have run into even more questions to be answered.


Author, Dan Yoshimoto attacking the beach at Lantzville (near Nanaimo) Vancouver Island,
British Columbia, Canada

Collection from
Airport Beach, Port Hardy, Vancouver Island, Canada

My interest peaked as my wife and I were collecting specimens of various gastropods between Humboldt County and Alaska and we thought that we had "discovered" 5-6 different species, that later turned out to be Nucella lamellosa. I showed the unnamed specimens to Dr. James H. McLean and Lindsey Groves, of the Malacology Department at the Los Angeles County Museum of Natural History. Of course they knew that I was a "very amateur" collector and kindly explained that they were all the same species. It was my first serious "adventure" into Conchology.


Hiromi (Wife) and a Giant Oyster in
Washington state 2002

Today we have collected Nucella lamellosa from over 40 locations and have bought, traded and had donated more than 30 specimens from a number of northern Alaska locations. 10 years later I am still fascinated with what I have learned. In a nutshell, here are a few facts:

  • Size: to 80mm
  • Habitat: Intertidal to subtidal (60 meters on submerged reefs and oyster beds)
  • Distribution: Aleutian Islands south to Santa Cruz, California and east to Sado Island, Japan
  • Food sources: Mytilus species, barnacles and various small bivalves
  • Predators: Sea Stars, Sea Gulls, Octopi, Crabs
Collection from
Tent Island, Straits of Georgia, off Vancouver Island, British Columbia, Canada

In 1998 I ran into a rather interesting volume of Trevor Kincaid's "Local Races and Clines in the Marine Gastropod Thais lamellosa Gmelin (A Population Study)". As it was my first "scientific introduction" to the species, and Mr. Kincaid was an expert, I took it for granted that the information was 100% valid, and that I no longer had to do any investigating. WRONG!!! I began to find contradictions in my own encounters that didn't hold up to Kincaid's "facts". I later ran into another scientific abstract by Robert R. Talmadge "Anomalies of Thais lamellosa" (Of Sea and Shore (1) 1973):35, in which he disputed the common conclusions held by many, including Kincaid.


Trio from
Vashon Island, Puget Sound, Washington


Here are a few assumptions that have been made by many observers:

1. The are 5 forms of Nucella lamellosa
(Dall, 1915-forms "franciscana", "neptunea", "hormica", "cymica" and "sitkana")
  • In reality there are many more, each with its own habitat niche.


King Salmon Village,
Humboldt County, California
2. Smooth forms are only frilled forms with the frills worn off in their rough surf pounding habitat.
  • In reality, smooth forms and rough forms can be found in the same populations in both the quiet and rough habitats.




Page Lagoon, Nanaimo, Vancouver Island, British Columbia, Canada
3. Each habitat has its own color forms.
  • In reality most habitats have variable coloring and patterning, from one color per specimen to striped and multicolored.




Ucluelet, Barkley Sound, Vancouver Island,
British Columbia, Canada
4. Frilled forms are found in quiet, protected bays and smooth forms are found in rough waters. Both forms are separated by sandy areas which are not crossed by the species.
  • In reality, often both forms are found crossing sandy areas from large rocks in bays.




Vashon Island, Puget Sound, Washington

In 2005 I gave a short talk and display to the Lost Coast Shell Club (Eureka, California) on the species Nucella lamellosa and from that meeting there came many questions which I could not answer, so I put the questions to the experts and other observers on Conch-L.

These are the questions and the responses that we received:


1. Q. What are the reasons for size differentiation in Nucella lamellosa?

A. Size is controlled by two things, food sources and genetics. Size is also important as the large shells usually have a lot more offspring, and at the same time have fewer predators... except for shell collectors.


Camano Island, Puget Sound, Washington

2. Q. What causes all the color and pattern variations, besides genetics?

A. Shell color is also controlled by what the animal eats .After many generations of evolution, those populations with single or maybe two colors/patterns, have become adapted to their environment and their predators. Those populations with many colors/patterns seem to have less predation.

Crescent City, Del Norte Co. California

3. Q. Why do some specimens have very thick shells and narrow aperture, while others have thinner shells and more fragile apertures?

A. Shells with thicker apertures and /or are frilly, have adapted to the crab predators that have a tendency to crush more fragile shells.

Tent Island, Staits of Georgia, off Vancoouver Island, British Columbia, Canada

4. Q. Could the color variations be forms of sexual dimorphism?

A. No.

Knight Island, Prince William Sound, Alaska

5. Q. Do the egg cases of Nucella lamellosa carry "veligers" that may float around and find new habitats, or are they "Walk away" juveniles, that are limited to their original habitat?

A. The Nucella species are "walk away" juveniles.

Nucella lamellosa egg cases ??
Suquash Beach, Port Hardy, British Columbia, Canada
ADDED NOTE: These egg cases are not from N. lamellosa (is it possible that N. lamellosa eats the egg cases of other Nucella sp.?). The eggs of N. lamellosa are tall, thin (not the short, squat eggs in your photo). I believe your eggs are N. ostrina." Rick Harbo

6.Q. Why do some specimens have "teeth" , or rows of teeth, in the aperture?

A. The teeth are there to help close off the aperture and keep out predators, such as crabs and birds.


Burnaby (Greater Vancouver area),
British Columbia, Canada

Wilson Creek, Del Norte Co., California


Because this species has so many forms, that have confused malacologists in the past, there are many names that have been used for Nucella lamellosa. When first described , it was called Buccinum plicatum by Martyn, in his Universal Conchylium, in 1788 and, in the same year, Chemnitz named it Buccinum compositum. Two years later (1791) the author, Gmelin called it Buccinum lamellosum. All three authors had placed the species in the family Buccinidae. The following are some more synonyms that have been used for this extremely variable species:


  • Buccinum crispatum Chemnitz
  • Polyplex rugosus Perry
  • Murex crispatus Lamarck
  • Murex ferrigineus Eschscholtz
  • Murex lactuca Eschscholtz
  • Polytropa crispata Lamarck
  • Purpura septentrionalis Reeve
  • Purpura (Polytropa) crispata Chemnitz
  • Purpura crispata Chemnitz
  • Thais (Nucella) lamellosa Gmelin
  • Thais plicata Martyn
  • Thais crispata Chemnitz
  • Thais etchegoinensis Arnold
  • Thais lamellosa Gmelin
  • Thais lamellosa var. franciscana Dall
  • Thais lamellosa var. hormica Dall
  • Thais lamellosa var. neptunea Dall
  • Thais lamellosa var. cymica Dall
  • Thais lamellosa var. sitkana Dall
  • Thais (Nucella) nomeana Dall
  • Thais (Nucella) shumanensis Carson

Sunset Bay, Coos Bay, Oregon

As there is never an ending to "discovery" my search for more information goes on.

Dan Yoshimoto


Silverdale, Dyes Inlet, Puget Sound, Kitsap Co. Washington



Abbott, R. Tucker Compendium of Seashells E.P. Dutton Inc. New York 1983

Dall, William Healy Notes on the Molluscan Genus Nucella Inhabiting the
Northwest Coast of America and Adjacent Regions Smithsonian Institute,
Government Printing Washington D.C. 1915

Harbo, Rick M. Shells & Shellfish of the Pacific Northwest Harbour
Publishing Madeira Park, B.C., Canada 2001

Kincaid, Trevor Local Races & Clines in the Marine Gastropod Thais
lamellosa Gmelin A Population Study The Calliostoma Company Seattle,
Washington 1957

Oldroyd, Ida Marine Shells of the West Coast of North America Stanford
Press, Palo Alto, California

San Diego Society of Natural History Pliocene & Pleistocene Mollusca of

Talmadge, Robert R. Anomalies of Thais lamellosa Of Sea & Shore Spring 1973


Bear Cove, Port Hardy, Vancouver Island, British Columbia Canada

Humbolt Bay, South Penninsula,
Humbolt Co., California