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).