Intertidal Zone Bioblitz

In 1940, John Steinbeck and Ed Ricketts chartered a purse seiner, the Western Flyer, for a 6-week expedition to the Sea of Cortez. They captured and catalogued marine invertebrates (animals without backbones) at 21 different sites along their route. In 1941, the two friends published Sea of Cortez, a narrative account of their journey and a “phyletic catalogue”of all the species they found. The catalogue includes 484 species of marine invertebrates!

This summer, the Western Flyer Foundation invites you to take an expedition to your local coastline to catalogue and identify as many marine invertebrates as you can using iNaturalist.

A Bioblitz is an event that focuses on finding and identifying as many species as possible in a specific area over a short period of time. The intertidal zone is the area of a seashore which is covered at high tide and uncovered at low tide.

To get involved, first download the iNaturalist app or open the iNaturalist website and login or create an account. Under projects, search for WFF Intertidal Zone Bioblitz and join the project. Visit the intertidal zone anytime during the summer, and use iNaturalist to take photographs and identify any living creatures you find! For tips about using iNaturalist, visit the website and watch their video tutorials or reach out to


Field Guide

Distinct species may be found in the intertidal zones at different latitudes, but, wherever you explore the intertidal, you will certainly find relatives of the species that Steinbeck and Ricketts found in the Sea of Cortez! We have created a field guide to help get you started. The field guide lists general groups (phylum, class, etc.) of the marine invertebrates listed in the phyletic catalogue of Sea of Cortez, based on Richard Brusca’s article The 1940 Ricketts-Steinbeck Sea of Cortez Expedition, with Annotated Lists of Species and Collection Sites*. 

Here are some other helpful field guides and resources:

SURMAR Field Guide to Common Rocky Intertidal Invertebrates of Baja California Sur created by William Gilly, Hopkins Marine Station, Stanford University 

SEANET Nearshore Plants and Animals of the Monterey Bay created by James Watanabe, Hopkins Marine Station, Stanford University.

Intertidal Invertebrates of Monterey Bay compiled and photographed by Gary McDonald, Long Marine Laboratory, University of California Santa Cruz 

* Brusca, R.C. (2020). The 1940 Ricketts-Steinbeck Sea of Cortez Expedition, with Annotated Lists of Species and Collection Sites. Journal of the Southwest 62(2), 218-334. doi:10.1353/jsw.2020.0016.