Barnacles are marine organisms commonly found attached to various submerged surfaces, including lobster shells. Their interaction with lobsters involves biological processes, from how they attach to their host to their potential effects on lobster health and behavior.
Barnacle Basics
Barnacles are marine crustaceans, distant relatives of crabs and lobsters. In their adult form, they are sessile arthropods, permanently attaching to a substrate. Their protective outer shell is typically composed of six calcareous plates.
Adult barnacles are filter feeders, using feathery appendages called cirri to strain microscopic organisms and detritus from the water. Their life cycle includes a free-swimming larval stage, beginning with nauplius larvae. These larvae molt through stages before transforming into a cyprid larva, which finds a suitable surface for permanent attachment.
Attachment to Lobsters
The attachment process begins with the cyprid larva. This larva actively searches for a settlement site, exploring surfaces using its antennae. Once a suitable location on the lobster’s exoskeleton is identified, the cyprid secretes a powerful, fast-curing adhesive, barnacle cement.
This natural adhesive allows the barnacle to permanently fix itself to the lobster’s shell. The cement is a protein-rich substance secreted from specialized glands near the barnacle’s base. Barnacles typically attach to hard surfaces like the lobster’s carapace, claws, and legs. The lobster’s molting cycle provides a temporary reprieve, as barnacles are shed with the old exoskeleton; however, new cyprid larvae can quickly recolonize the freshly molted shell.
Impact on Lobsters
The presence of barnacles on lobsters can range from negligible to significantly detrimental, depending on the infestation level and the lobster’s overall health. A few barnacles usually pose no harm. However, a heavy accumulation can lead to several challenges.
Increased weight and hydrodynamic drag force the lobster to expend more energy for movement, hunting, and escaping predators. Severe infestations can also interfere with the molting process, making it difficult for the lobster to shed its old shell, which is essential for growth. Heavy barnacle loads may cause irritation or create entry points for secondary infections at attachment sites. Lobsters heavily encrusted with barnacles may also be less marketable due to aesthetic reasons.
Prevalence and Common Types
Barnacles are common on lobsters, their prevalence influenced by several environmental and biological factors. Water temperature, salinity, and the lobster’s health and age all play a role. Older lobsters, which molt less frequently, tend to accumulate more barnacles.
The types of barnacles found on lobsters are typically “acorn” barnacles. Species such as Balanus crenatus and Chthamalus stellatus are frequently observed. Balanus crenatus is a widespread species found in the North Pacific and North Atlantic, attaching to various hard substrates, including crustacean carapaces. Chthamalus stellatus is another acorn barnacle common on rocky shores, attaching to firm materials.