Vekhova E.E., Kiselev K.V.
Zoologicheskiy zhurnal 2025; 104(5): 3-17
Morphological structures of the byssal apparatus, byssal threads and byssal groove of the foot of the commercial Mediterranean mussel (Mytilus galloprovincialis) from the Sea of Japan are studied. The byssal apparatus is shown to consist of a root, a stem and the byssal threads, these being of ellipsoid shape in cross--section. Each byssal thread consists of a corrugated, wide proximal part located immediately behind a cuff and is ⅓ of its length, and a relatively elastic, narrow distal part (⅔ of thread length) ending with an oval attachment disk at the distal end. In the composition of each byssal thread in its different parts are contained the byssal prepolymerized collagens - P, D, NG, which have the different in nature block copolymer structure. The surface of byssal threads is tuberous all along. On the surface of the attachment disk, two reinforcing cords are present. The edges of the attachment disks are semitransparent. The byssal groove of the foot is more primitive in structure than in the other species of mytilids studied. It is noteworthy that a distal fossa is absent at the distal end of the byssal groove of the foot. The above features of the morphological structure of the byssus and attachment disks in M. galloprovincialis are explained by structural differences of the secretory organ.
