- Barnacles are small invertebrates that live inside hard circular or pyramid-like structures made from calcium-carbonate.
- Honeycomb barnacles are normally found clustered together in large numbers (colonies) and can share walls, giving them an appearance of a bee’s honeycomb.
- Their shell is made up of 4 sided plates, which are either white or grey in colour.
- It’s rare to see the animal living inside, they only come out at high tide or when feeding.
- Size: 5-19mm in height, 5-8mm in diameter.
What to Observe
Search the area for 30 minutes and record 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
Honeycomb 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
Where To Look
- Common on rocky shores, from high to mid tide levels. Usually found on exposed rocky surfaces of the high shore.
- Eastern SA, Northern-eastern TAS, VIC and NSW.
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.
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. Honey comb barnacles can be distinguished from other barnacles as they are usually clustered together, with some individuals sharing common walls, resembling honey comb or wasp’s nests.
Did You Know?
Honeycomb barnacles are only found on rock surfaces, never on wood.
Barnacles are filter feeders- they grab passing food from the water with their two, feather like arms.
Barnacles are related to crabs and lobsters