Pacific Pup: The California Coast According to Annette


Stickin’ on the Dock of the Bay

Exploring California wharfs and piers is always exciting, and not just for the people-watching, good food, and silly souvenirs. I can’t help but smile when I see animals using man-made structures like these as prime real estate. Underneath all the excitement and human activity lies a surprisingly diverse community of animals. Mussels, barnacles, limpets, and many other creatures adhere themselves in fascinating ways to the sturdy columns supporting our piers. These animals are professional clingers, and researchers study their amazing ability to attach for practical applications (in dentistry and medicine, for example).
At first glance, mussel pilings, or “beds,” as they are referred to, just look like solid, inanimate mounds of sharp rocks. It is hard to believe that these are living, breathing creatures! Underneath the surface, mussels open their shells slightly and release tiny hairs called “cilia.” With their cilia, mussels filter up to twenty gallons of water every day, feeding on plankton and tiny plant matter. They also produce a liquid adherent called a byssal thread that attaches them to rocks, piers, or other mussels. The thread trails out of a specialized gland, and once it is exposed to ocean water, it solidifies into a very strong fiber. California Mussels are edible, and in some areas you can collect them. This is a fun recreational activity, but keep in mind that overcollecting would surely lead to disturbance of habitat or worse, extinction.
Rough Limpets and Acorn Barnacles are wonderfully bizarre creatures that cling stubbornly to wharfs and piers. Don’t underestimate the strength of any tiny limpet. Over time, limpets use the rough scalloped edges of their shells to grind into the surface of rocks. Talk about stuck in a rut! Acorn barnacles, on the other hand, produce a super-powerful adhesive with what scientists decided to call a “cement” gland. Not even acids or alkalis can dissolve this tough glue. Barnacles are extremely successful colonizers–some say too successful. In less than two years, ten tons of barnacles can attach to the inside or outside of a commercial tanker. This causes major fuel efficiency problems and introduces non-native species to vulnerable ecosystems.
There are literally thousands of other critters that grace us with their presence at wharfs and docks. The next time you’re enjoying some California sun on a pier, be sure to pay a visit to a wharf piling. They are literally overflowing with life-forms! Check out these fun and beautiful works of art by Sarah McNaboe and Jane Kim that capture some of our California crustaceans.
See you at the beach!
Annette Filice
(Scientific Illustrator Intern)

Sketch Notes:
Stickin’ on the dock of the Bay
California Mussels, Acorn Barnacles, and limpets are just a few of the animals that use fascinating methods to cling to California’s beloved piers and wharfs.
California Mussel, Acorn Barnacle, limpets, Purple Sea star


  1. says

    Stickinonthedockofthebay.. Very nice 🙂

  2. says

    Stickinonthedockofthebay.. Super 🙂

  3. says

    Stickinonthedockofthebay.. Nifty 🙂