Poway woman’s fascination with seashells led to a guidebook for county

Judy Carlstrom’s fascination with seashells started in 2003 when she drove along the coast from San Diego to Eureka. That led to her interest in hiking along the beach.

“I realized I hadn’t done much exploring of beaches until then,” said Carlstrom, 74, of Poway. “I became fascinated after my first drive up the coast of California. When I started hiking, I thought about how I wanted to collect these shells and see what they were.”

What she’s researched and learned about seashells as a self-described “citizen scientist” since then led her to write the recently published book, “Seashells of San Diego County and the Animals Within Them.”

The 64-page guide published by Chula Vista-based Sunbelt Publications helps people identify modern marine invertebrates, said the former elementary school teacher. The book tells readers how to identify what creatures formerly lived inside a variety of seashells based on the characteristics of individual shells, she said.

Most of the specimens are what could be found washed up on a beach alongside seaweeds and driftwood. The curiosities are not ordinarily collected from tidepools because those are habitats for living crustaceans, she said.

“A lot of times they’re only partial shells,” she said. “My focus is to get people to have fun figuring out what it is based on a piece of a shell. I don’t want them to be discouraged if they don’t find a beautiful shell in its entirety.”

Generally shells are divided into bi-valves and gastropods, Carlstrom said. The gastropods, which are similar to snails, are generally more plentiful on the beaches. Carlstrom says she included about 80 species of seashells that are most commonly found on the beaches in her guidebook.

While teaching fifth-graders in Escondido for 20 years at a public school named North Broadway Elementary School, Carlstrom would take her students on field trips to tidepools so they could research and write mollusk reports. The students usually created their own field guides with original drawings and items gathered from the beach, she said.

Other nature-inspired lessons involved collecting plants for the Plant Atlas Project, Carlstrom said.

Led by the San Diego Natural History Museum, the project started in the early 2000s as a way for the museum to collect one specimen of every species of plant in San Diego County. Trained volunteers would gather the plants within 3-square-mile spaces, she said.

Her students brought their own specimens to the museum, where they toured the Botany Department and observed the prior year’s class of specimens mounted in drawers. The plants collected by students and volunteers have been compiled into a database that has grown to the point that most plants in the county have been identified, Carlstrom added.

“I think it’s very meaningful for children who are 10 years old to have direct contact with the natural world and the ability to develop curiosity,” she said, noting that her seashell book is written for adults but can easily be used by children with guidance.

Carlstrom has been volunteering for the San Diego Natural History Museum for 22 years in other ways, too.

From 2006 to 2018, she worked in the museum’s Botany Department. Much of her work involved mounting plant specimens on archival paper for storage.

But in 2018, just two years after retiring as a school teacher, Carlstrom said she replied to an internal email at the museum seeking someone to identify micro-fossils that are marine invertebrates from Baja California, Mexico. The fossils were from the Pleistocene Period, she said.

“It’s mostly just me and one other person identifying micro-fossils which are invertebrates,” said Carlstrom, who has lived in Poway since 1982 and whose three children graduated from Poway High School. “The staff does get involved to a certain point in the identification. They have to verify the IDs before they put the permanent tags on them.”

The author also volunteered as a Torrey Pines State Reserve docent for four years in the 1980s. Carlstrom said she learned about native plants, but not a lot about seashells while she led guided hikes in the reserve.

“We never got down to the beach to discuss shells,” she said. “It was always up in the reserve.”

Carlstrom said her book focuses on seashells in the county because in her quest to learn about local shells, she was disappointed to find so few resources.

The “Petersen Field Guide to Pacific Coast Shells” was out of print, although she managed to find one at a thrift shop. She found more out-of-print books online, at thrift shops and at the San Diego Shell Club’s annual show, she said.

“The beautiful books published by the Santa Barbara Museum of Natural History only covered bivalves, the National Audubon Society’s book covered all of North America, and the rest that I could find were even more general, so I decided to create my own small guide,” she said.

“It is by no means complete, but I have simply tied together as much information as possible for the shells most commonly found along the shores of San Diego County.”

The most common seashells found locally include the California Venus, Tellins and the Donax, she said.

The guidebook filled with pictures she’s drawn and photographed of seashells is small enough that it can be taken to the beach and used as a reference and resource, she said.

Since her interest in shells was piqued more than two decades ago, Carlstrom said she has acquired a fairly large collection of her own shells.

“I’m still missing some of the obscure deep water shells but I have most of what you would commonly find,” she said. “I didn’t want to frustrate people by putting items in the book that are rarely found on the beach.”

Copies of her paperback priced at $12.95 are available at bookstores and on the Sunbelt Publications website, SunbeltPublications.com. Copies can also be found at San Diego County libraries.