Northern rock barnacle

Northern rock barnacle
(𝑩𝒂𝒍𝒂𝒏𝒖𝒔 𝒃𝒂𝒍𝒂𝒏𝒐𝒊𝒅𝒆𝒔) 
Conservation Status: No Current Status Rank  

Photo Credit:  Neil DeMaster/Flickr 

This creature may easily be overlooked in the wild—that is until you step on them with your bare feet. Ouch! These small animals are called barnacles! Barnacles are similar to  shrimp, and have overlapping limestone plates which protect them from predators. While barnacles may all look the same, if you look closely you can tell that there are many different species. Here in Southern Maine, you might see the acorn barnacle, which is very small, from 2.5 cm to 7.5 cm, and is shaped like an acorn. Planted on the rocks for the majority of life, these creatures must feed on the phytoplankton that passes over them as the tides ebb and flow. How do they do it? They reach out a feather-like foot – called cirri— catching and eating the plankton which floats by. If you look closely as the tide comes in, you can spot the feather-like structure moving in the current. When the tide is out, you will see them tightly closed as to protect themselves from weather elements, such as the heat and drying of the sun or stormy rain and ice.  

Barnacles can be found not only all over our beaches, but all over the world. At the refuge you might see them covering rocks and other hard structures on the banks, or scattered across the intertidal zone. Barnacles can be found everywhere from the hightide line of the beaches in Maine to the hull of a ship, and even on the back of a whale. That is because young barnacles, before planting down, float with the currents all over the world until they find a nice spot to land – whether it’s a rock on the banks of Rachel Carson National Wildlife Refuge or on the shell of a turtle. Although most ocean species pay no mind to barnacles, sea slugs, dog whelks, flatworms and the ever-popular sea stars feast on them. 

Fun Fact: The cement that northern rock barnacles use to attach themselves to hard rock surfaces is currently being studied for dental applications.  

Sources: https://animaldiversity.org/accounts/Semibalanus_balanoides/, https://www.seacoastsciencecenter.org/2016/04/20/northern-rock-barnacle-feeding/, http://www.edc.uri.edu/restoration/html/gallery/invert/north.htm