Acorn Barnacle
Scientific Name: Balanus glandula
Category: other
Brief Description
A sessile crustacean that attaches itself permanently to hard surfaces like rocks or docks.
Characteristics
Hard, cone-shaped white or grayish shells composed of several calcareous plates with an opening at the top.
Habitat
Intertidal zones, attached to rocks, pier pilings, and shells in marine environments.
When to Find It
Visible year-round, especially during low tide in the Puget Sound area.
Conservation Status
Common/Not Threatened
Ecological Role
Barnacles are filter feeders that clarify water and serve as a primary food source for sea stars, snails, and certain fish.
Easily Confused With
Limpets (which have a single un-segmented cap-like shell) and Gooseneck Barnacles (which have a fleshy stalk).
Observation Tips
Look for them in the mid-to-high intertidal zone during low tide. Be careful as their shells are very sharp; wear sturdy shoes.
Interesting Facts
Despite looking like mollusks, barnacles are actually crustaceans, making them more closely related to crabs and lobsters.
User Notes
Puget sound