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Photo of a Giant Acorn Barnacle

Species profile

Giant Acorn Barnacle

Balanus nubilus

Barnacles2.1K iNat observations

At a glance

Giant Acorn Barnacle (Balanus nubilus) is a barnacle regulated in 2 of 66 jurisdictions tracked by CatchRules across the U.S. and Canada.

Bag limits are uniform at 6 per angler across the 2 regulating jurisdictions.

Confirmed by 1,060 research-grade iNaturalist observations, with British Columbia, California, and Washington the top jurisdictions by observation count.

Notable details

  • One of the world's largest barnacle species, reaching up to 7 cm (3 inches) tall.
  • Found along the Pacific coast from Alaska to Baja California on rocks and pilings.
  • Sweeps the water with feathery cirri to capture plankton and organic particles.
  • Can live 10–15 years, making it one of the longest-lived barnacle species.
  • Once attached as an adult, it cements itself to hard surfaces permanently and never moves.

Background

Balanus nubilus, commonly called the giant acorn barnacle, is the world's largest barnacle, reaching a diameter of 15 centimetres (5.9 in) and a height of up to 30 centimetres (12 in), and containing the largest known muscle fibres.

Background excerpt adapted from Wikipedia's Giant Acorn Barnacle article (CC BY-SA). Visit Wikipedia for the full entry.

Photo credit: iNaturalist / Wikipedia. Identification reference only — verify regulations with the issuing wildlife agency before retaining a catch.