Baker, Shirley M., Jeffrey S. Levinton, and J. Evan Ward. 2000. Particle transport in the zebra mussel, Dreissena polymorpha (Pallas). Biol. Bull 199: 116-125.

To view the video, click the links below. When the video plays, double click the video image to replay.

Video A. Inner and outer demibranchs of Dreissena polymorpha as observed through the endoscope (looking dorso-anteriorly). The visceral mass is on the left, inner demibranch (and its marginal groove) in the center of the frame, and outer demibranch on the right. The outer demibranch is just visible in the lower right-hand background before the inner demibranch moves to the right. The demibranchs are held curved towards the visceral mass. These gill postures are maintained despite variation in the overall orientation of the mussels.

Video B. Inner demibranch of Dreissena polymorpha as observed through the endoscope (looking medially). Side view of the ventral margin of the inner demibranch (center of frame) and the visceral mass (background). Particles (green alga, Scenedesmus quadricauda) are moving anteriorly in the superficial groove of the ventral margin. The presence of a superficial mucous string, as opposed to particle slurry, is confirmed in this sequence in which the string is dislodged from the ventral margin by a contraction of the gill. The superficial mucous string remains unbroken and returns to the ventral margin of the demibranch.

Video C. Ventral margin of the inner demibranch of Dreissena polymorpha as observed through the endoscope (looking dorsally). Polystyrene beads and the green alga, Secnedemus quadricauda, are moving anteriorly in the superficial mucous string. Particles approaching the ventral margin of the inner demibranch enter the mucous strings in different ways. Here, a particle (polystyrene bead, right) on the ascending lamella of the inner demibranch (upper) moves ventrally on the frontal surface of a filament. Once it reaches the filament tip, nearing the food groove, it moves laterally (to the left in this case) and enters the marginal groove proper through gaps between the filament tips.

Video D. Inner demibranch and pair of labial palp lamellae of Dreissena polymorpha as observed through the endoscope (looking medially; ventral is toward the bottom of the frame). Here, the distal apices of the palp lamellae enclose the ventral margin of the inner demibranch. The superficial mucous string is drawn from the ventral margin of the inner demibranch and the particles disperse on the palps (not shown). Here, a ball of mucus (pseudofeces) is forming on the ventral margin of the palp lamellae (bottom right).