Barnacles are marine crustaceans, distantly related to crabs and lobsters. Unlike their mobile relatives, adult barnacles are sessile, attaching permanently to surfaces like rocks, ship hulls, or other marine animals. They possess a hard, multi-plated calcareous shell for protection. As filter feeders, barnacles use specialized, feathery appendages called cirri to capture microscopic plankton and detritus from the water.
Key Marine Predators of Barnacles
Despite their protective shells, barnacles are a food source for numerous marine animals. Sea snails, particularly whelks, are significant predators. These predatory snails use a specialized, rasping radula to drill a precise hole through the barnacle’s hard shell. Once penetrated, the whelk accesses and consumes the soft body inside. Some whelks also secrete an acid to assist in dissolving the shell.
Starfish, such as the Ochre Sea Star, also prey on barnacles. They use their tube feet to exert continuous pulling pressure on the barnacle’s shell plates until an opening is created. Some starfish can also evert their stomachs into the barnacle’s shell to digest the soft tissues externally.
Various fish species also prey on barnacles. Sheepshead fish, with their strong, human-like teeth and powerful jaws, crush barnacle shells, often scraping them off rocks and pilings. Other fish like triggerfish and some puffers also have strong beaks and jaws capable of crushing barnacle shells.
Crabs are opportunistic predators that feed on barnacles. They use their strong claws to crush barnacle shells and access the soft body inside.
Shorebirds and gulls also consume barnacles, especially during low tide when barnacles are exposed on rocks and other surfaces. These birds use their beaks to pick or pry barnacles off, which helps regulate barnacle populations in intertidal zones.
The Role of Barnacles in the Food Web
Barnacles hold a significant position in marine food webs as primary consumers. As filter feeders, they consume microscopic phytoplankton and zooplankton. This feeding habit transfers energy from these tiny organisms to higher trophic levels.
Their role as a food source is widespread across various marine and intertidal ecosystems. By converting plankton into their own biomass, barnacles provide a readily available energy source for a diverse array of predators.
Their abundance and widespread distribution make them a foundational link in many coastal food chains, integral to energy flow from the base of the food web to larger marine animals. Their continuous filtering also contributes to water clarity, indirectly benefiting the ecosystem by allowing sunlight to penetrate deeper for photosynthetic organisms. Barnacles thus help maintain the balance and health of marine environments.