An initiative of Earthwatch Institute

  1. Surf4_elvira_poloczanska-cropped 20mm (height) & 25-30mm (diameter) by Elvira Poloczanska
  2. Surf3_amber-louise_burberry Surf Barnacle by Amber-Louise Burberry
  3. Surf5_elvira_poloczanska Close up of Surf Barnacle (8 main plates surrounded by small plates) by Elvira Poloczanska

Surf Barnacle

Catomerus polymerus


  • Barnacles are small invertebrates that live inside hard circular or pyramid-like structures made from calcium-carbonate
  • Surf barnacles have 8 main side plates, surrounded by many smaller ones, giving them a scaly appearance and are usually grey with a greenish tinges.
  • Size:  20mm height, 25-30mm diameter




What to Observe

Search area for 30 minutes and record under the following categories:

  • Abundant - found easily with little searching
  • Frequent - found with minimal searching
  • Rare - only 1 or 2 individuals found with intensive searching
  • Not found - not present during search

ClimateWatch Science Advisor

Surf barnacles are under increasing stress due to ocean acidification which can weaken their calcium carbonate shells and reduce body condition. This makes them more prone to disease, predation and low reproduction. Increasing water temperature as a result of climate change will likely affect their abundance and cause a southward shift in their distribution.

When To Look

All year

Where To Look

  • Common on rocky shores, from mid to low tide, particularly areas of high wave exposure.
  • Southern WA, SA, TAS and NSW. 

Surf Barnacle distribution map - GBIF

Surf Barnacle distribution map - GBIF



Davey, K. (1998). A Photographic Guide to Seashore Life of Australia. New Holland Publishers Australia Pty Ltd.

Edger, GJ. (2008). Australian Marine Life. The Plants and Animals of Temperate Waters [2nd Ed]. New Holland Publishers Australia Pty Ltd.


  1. Search Species

  1. What Else?

    Barnacles can resemble limpets as both are round, pyramid-shaped and cream in colour. Barnacles can be distinguished from limpets by their shells, which are always made up of multiple plates.  Limpets always have shells that consist of only one singular plate. Limpets are also free moving whereas barnacles are always fixed to a hard surface. Surf barnacles have a distinctive scaly appearance and are found in areas of high wave exposure.

  1. Did You Know?

    They are called surf barnacles because they prefer to live in areas of med to high energy wave action.