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.

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

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.

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

• In reality there are many more, each with its own habitat niche.

• In reality, smooth forms and rough forms can be found in the same populations in both the quiet and rough habitats.

• In reality most habitats have variable coloring and patterning, from one color per specimen to striped and multicolored.

• In reality, often both forms are found crossing sandy areas from large rocks in bays.

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.

 

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.

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.

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

A. No.

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.

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.

 

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

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

Dan Yoshimoto
yoshells2@humboldt1.com