balanus glandula

{{Short description|Species of barnacle}}

{{Speciesbox

| image = Balanus glandula01.jpg

| image_caption = Balanus glandula with Chthamalus fissus

| genus = Balanus

| species = glandula

| authority = Darwin, 1854

}}

Balanus glandula (commonly known as the North American acorn barnacle or common acorn barnacle) is one of the most common barnacle species on the Pacific coast of North America, distributed from the U.S. state of Alaska to Bahía de San Quintín near San Quintín, Baja California. They are commonly found in the upper intertidal zone on mussels, rocks and pier pilings.{{cite book|author=Robert Hugh Morris, Donald Putnam Abbott & Eugene Clinton Haderlie |year=1980 |title=Intertidal Invertebrates of California |publisher=Stanford University Press |location=Stanford |isbn=978-0-8047-1045-9 |chapter=Balanus glandula |pages=520–521 |chapter-url=https://books.google.com/books?id=NAybxQZvWI0C&pg=PA520}} They can obtain oxygen from both water and air.{{cite web | url= http://eol.org/pages/1020180/overview | title= Balanus glandula — Overview | last= Rosario Beach Marine Laboratory | author-link= Rosario Beach Marine Laboratory | date= | website= Encyclopedia of Life | access-date= 2018-08-15}}

This acorn barnacle is a moderate-sized one with a diameter of up to {{convert|22|mm|1|abbr=on}}. The shell is formed by overlapping plates and has a calcareous basis. It has more the shape of a cylinder than the shape of a cone. The white operculum has heavily ridged walls. It can live up to ten years.

It has been intensely studied in recent years as a model species for linking physical oceanography and population genetics (or phylogeography) surveys.{{cite journal |author1=Erik Sotka |author2=John Wares |author3=Jack Barth |author4=Rick Grosberg |author5=Steve Palumbi |author-link5=Steve Palumbi |year=2004|title=Strong genetic clines and geographical variation in gene flow in the rocky intertidal barnacle Balanus glandula|journal=Molecular Ecology|volume=13|issue=8|pages=2143–2156 |doi=10.1111/j.1365-294x.2004.02225.x|pmid=15245390 |s2cid=18401309 }} This species was introduced to the shores of Argentina in the 1960s, and has become an invasive species, displacing other barnacles and mussels.Zaixso, H.E., Boraso de Zaixso, A.L., Pastor de Ward, C.T., Lizarralde, Z., Dadón, J.R. and Galván, D. 2015. Capítulo 2. El bentos costero patagónico. In: Zaixso, H.E., A.L. Boraso de Zaixso, C.T. Pastor de Ward, Z. Lizarralde, J.R. Dadón and D. Galván (Eds.), La Zona Costera Patagónica Argentina. Volumen II. Comunidades Biológicas y Geología, Editorial Universitaria de la Patagonia, Comodoro Rivadavia, pp. 43–152.{{cite journal |author=Evangelina Schwindt|year=2007 |title=The invasion of the acorn barnacle Balanus glandula in the south-western Atlantic 40 years later |journal=Journal of the Marine Biological Association of the United Kingdom |volume=87 |issue=5 |pages=1219–1225 |doi=10.1017/S0025315407056895|hdl=11336/103239 |hdl-access=free }}