Barnacles are common marine creatures found clinging to rocks, docks, and various submerged surfaces in intertidal zones. Their hard, irregular shells often lead people to perceive them as sharp. Understanding their nature clarifies why they can feel abrasive to the touch and how their physical structure contributes to this characteristic. This article explores the material science of their shells and the biological processes that create their jagged surfaces.
The Composition of Barnacle Shells
Barnacle shells are primarily composed of calcium carbonate, a hard, crystalline mineral. This material is similar to limestone or the shells of other marine organisms like mollusks. The mineral component often exceeds 92% of the shell’s weight. While some warm-water barnacle species may incorporate aragonite, another form of calcium carbonate, the dominant structure is calcitic.
Calcium carbonate provides the barnacle shell with its rigid, protective outer layer. While not inherently sharp like a blade, its crystalline structure gives it abrasive qualities. The material’s hardness means contact can result in scrapes or cuts, especially when combined with the irregular shapes formed during growth. Organic components, including proteins, are also integrated into the shell, playing a role in its formation and overall structure.
How Barnacles Create Jagged Surfaces
As adults, barnacles are sessile organisms, meaning they permanently attach themselves to a chosen substrate. They achieve this firm attachment using a highly effective protein-based adhesive, often called barnacle cement. This natural cement is exceptionally strong, capable of withstanding significant forces, allowing them to bond to diverse surfaces even underwater. The larval stage secretes this adhesive after selecting a suitable location.
As barnacles grow, their shells enlarge by continuously secreting calcium carbonate and organic matrix proteins from their mantle tissue. This incremental deposition adds new layers to the existing shell plates, which interlock to form a protective casing. When many barnacles settle close together, their individual shells can fuse and overlap, forming dense, uneven clusters. These clusters, especially when disturbed or when a barnacle dies, often present exposed, broken edges or sharp ridges that contribute to their perceived sharpness.
Avoiding Barnacle-Related Scrapes
Encounters with barnacles often occur in intertidal zones, where they colonize rocks, or when handling marine equipment like ropes and boat hulls. To minimize the risk of scrapes, wearing appropriate protective footwear is beneficial. Water shoes with thick, puncture-resistant rubber soles or sturdy sandals can protect feet from sharp surfaces. Rubber boots are also a good option for keeping feet dry and providing traction on slippery, barnacle-covered rocks.
When handling marine gear encrusted with barnacles, using gloves can prevent cuts to the hands. Specialized marine gloves, often made from neoprene or with reinforced palms, offer increased durability and protection. Exercising caution and being mindful of surroundings in barnacle-rich environments is also key. If a scrape occurs, clean the wound thoroughly with soap and water, then flush it with clean water to prevent infection. Applying an antiseptic ointment and covering the wound with a dressing can further aid healing.