An initiative of Earthwatch Institute

  1. Peri5_amber-louise_burberry Size compared to 5 cent coin by AL Burberry
  2. Peri3_amber-louise_burberry 10-15mm in size by AL Burberry

Blue Periwinkle

Austrolittorina unifasciata


  • Blue periwinkles or Australwinks are small marine snails (molluscs) 
  • They are light blue to grey in colour and have a smooth shell that spirals up to a light brown to reddish-brown sharp tip (apex).
  • Size:  10-15mm

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

Australwinks, like all marine snails (molluscs), 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

Throughout the year

Where To Look

  • Common on rocky shores, from high tide level to wave splash zone. Usually found very high up the platform where there is little to no standing water. 
  • North Western Cape WA, SA, TAS, VIC, NSW up to Yeppoon QLD. 

Blue Periwinkle distribution map - GBIF

Blue Periwinkle 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?

    Australwinks or Blue Periwinkles are able to live high up on the shore, a feature which separates them from most other marine snails. Noddiwinks also live high up on the shore but they can be separated from Australwinks by their easily seen nodules or bumps on their shells. Blue periwinkles are smooth shelled and slightly smaller in size.

  1. Did You Know?

    The larger periwinkles are found higher up the platform. The furthest one has been recorded from the high tide level is 10 metres.

    Australwinks are herbivores and scrape lichens from the rock with a specialised tongue called a radula.