Acorn Barnacle 7695109434 O
57Identifcation number on The Map®

Acorn Barnacle

Balanus glandula

Acorn BarnacleKevin Lee ~


  • This very large unstalked, sessile barnacle is not easily confused with any other species
  • Has a large aperture and lacks longitudinal striations on any of the large body plates
  • Size Diameter to 4 inches
  • Height to about 3 inches


  • Southern Alaska to La Jolla, California


  • Attached to rocks and pier pilings; low intertidal zone to depths of at least 300 feet


  • Filter feeds on plankton and edible detritus

Interesting Facts

  • Sometimes eaten by sea otters, sea stars, and crabs