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 crenatus has a shell comprised of six shell plates, which forms a volcano-like cover. The shell plates are white and smooth and in large individuals the upper edges of the shell plates are usually slightly toothed or ridged. The shell is inclined to one end when viewed in profile. The base of the shell is calcareous with an average basal diameter of 25 mm.
Environment and Habitat
- Epifaunal, principally in the sublittoral but can be found in cryptic environments on the lower shore.
- 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
- Commonly found on western and southern coasts of the UK and Ireland, not so frequently on north eastern shores. Range runs from Norway in the north to the Atlantic coasts of France in the south.
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