Type of fouling organism: Barnacle
Barnacles are a unique, and much modified group within the Phylum Crustacea. All barnacles are sessile marine animals, which remain fastened to hard substrates. When the barnacle is immersed under water, the upper shell plates open and the legs reach out casting a food collecting net. These basket like limbs are called cirri and filter food from the water and direct it towards the mouth. Barnacles have both male and female organs (hermaphroditic) and are all able to fertilise one another. As the adult stage is sessile, motile larval stages living in the plankton are the main method of dispersal. Barnacle larvae develop through a number of planktonic stages with the rate determined by feeding rate and temperature.
Balanus perforatus is a darkly coloured volcano shaped barnacle with a small oval shaped aperture. It has a calcareous base that can be up to 30 mm in diameter. Larger individuals are found in the subtidal and plates protrude above the operculum. The shell is comprised of six purple plates which are often vertically ridged.
Environment and Habitat
- Found from the mid-shore intertidal down into the shallow subtidal on hard substrates.
- Reproductive type: Hermaphrodite.
- Found on other biofouling organisms.
Effects and Impacts
- Problematic for stock species as can compete for space and resources.
Control/ Strategies and Management
Principles of Management
C Combat Settlement
- Widespread throughout south east England and south to West Africa and the Mediterranean.
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