The Byssus Morphology and Strength of Attachment to Substrate in the Bivalve Mollusk Arca boucardi Jousseaume, 1894 (Arcidae)

AbstractWe observed the behavior of the bivalve mollusk Arca boucardi during reattachment of the mollusk to plexiglass. According to our observations, after 0.5–4 h of active movement in search of a suitable place, the mollusks began to form a byssus and secreted a transparent discharge. After 9–10 h a new byssus formed, which did not fundamentally differ from the old one. It was shown that the byssus is a monolithic relatively elastic green band with an adhesive sole in the distal part and a system of septa in the proximal cavity that serves for attaching the muscles responsible for the byssus function. Field studies to evaluate the adhesion strength of mollusks to the substrate have shown that the strength varies from a few hundred grams to 23.5 kg, depending on the size of mollusk. The data are discussed in terms of the functional morphology and peculiarities of the spatial distribution of A. boucardi in the upper subintertidal zone.