Fig. 3. Feeding behaviour of the zebra mussel Dreissena polymorpha. (A–F) Frames from videos; (A–D) side views, (E,F) underside views. (A) Pseudofaecal material expelled by the inhalant siphon of the mussels when fed the non-toxic diatom Asterionella formosa. (B) Faecal material expelled by the exhalant siphon of the zebra mussel when fed the diatom Asterionella formosa. (C) Copious pseudofaecal material expelled by the inhalant siphon and copious pseudodiarrhoea expelled through the pedal gape of the zebra mussel when fed the toxic cyanobacteria Microcystis aeruginosa (strain CCAP 1450/10). (D) Copious faecal material expelled by the exhalant siphon and copious pseudodiarrhoeal material expelled through the pedal gape of the zebra mussel when fed the toxic cyanobacteria Microcystis aeruginosa (strain CCAP 1450/10). (E,F) Pseudofaecal material expelled by the inhalant siphon and pseudodiarrhoeal material expelled through the pedal gape of the zebra mussel when fed the toxic cyanobacteria Microcystis aeruginosa (strain CCAP 1450/10). InS, Inhalant siphon; ExS, exhalant siphon; Pg, pedal gape; PIn, pseudofaeces expelled through the inhalant siphon; FEx, faeces expelled through the exhalant siphon; PPg, pseudodiarrhoea expelled at the pedal gape.