E-Fauna BC: Electronic Atlas of the Wildlife of British Columbia

Semibalanus cariosus (Pallas, 1788)
Thatched Barnacle
Family: Archaeobalanidae
Species account author: Ira Cornwall.
Extracted from The Barnacles of British Columbia (1955).
Photo of species

© Derek Holzapfel  Email the photographer   (Photo ID #14912)

E-Fauna BC Static Map
Distribution of Semibalanus cariosus in British Columbia
Details about map content are available here.

Species Information


The size varies greatly up to 1¼ inches in diameter and 2½ inches in height. The normal shell is a steep-walled cone with numerous downward-pointing spines, giving it a "thatched" appearance. When crowded they take on a tubular form and may lack the spines. The base is membranous.


White in young or uncrowded individuals; otherwise dirty grey.


Coasts of Western North America and Japan. At about the quarter-tide level, on rock.


On the British Columbia coast this is the only large barnacle with a membranous base. It is usually found on the rocks, and much crowded.

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Additional Photo Sources

General References

Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2021. E-Fauna BC: Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [Accessed: 2024-07-23 1:41:38 AM]
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© E-Fauna BC 2021: An initiative of the Spatial Data Lab, Department of Geography, UBC