Barnacles, A Lasting Attachment

May 29, 2018


Photographer: Patricia Weeks 
Summary Author: Patricia Weeks 

There are over 1,200 species of barnacles worldwide. Although they resemble mollusks, barnacles are crustaceans and are related to lobsters and crabs. As sessile (or immobile) organisms, barnacles are often found in shallow waters and affix themselves to piers, rocks, vessels and even other sea creatures. After finding the ideal location to make its home, each barnacle attaches itself permanently with one of the most powerful glues found in nature. In fact, it has an adhesive strength of 22–60 pounds per square inch. Sometimes called crusty foulers, barnacles are the bane of boaters’ existence, as they're almost impossible to remove. They can cause up to 60 percent more weight and drag for naval ships and add nearly 40 percent more fuel usage.

Each barnacle encases itself with a cone of 6 calcium plates. It creates 4 more plates as a door that opens to allow its feathery appendages, called cirri, to gather plankton for food, and that closes in case of a threat or when low water levels expose them. Barnacles colonize in tight communities, for protection and reproduction. Each barnacle is hermaphroditic and depends on its neighbor for fertilization. A newborn free-floating larva feeds on plankton, and when mature enough, locates the best possible place to attach itself, and the entire life process is perpetuated.

This photo shows a colony of barnacle encasements, which appear to be empty, on a pier post on the Pamlico River waterfront in Washington, North Carolina. Photo taken March 18, 2018.

Photo Details: SONY DSC-HX400V camera; 90.22 mm focal length; f/5.6 aperture; 1/250 exposure; ISO 100.