A large planktonic ciliate, Pseudotontonia cornuta, was observed during a cruise in the North Sea, Denmark, in summer 2001. Live cells as well as fixed and protargol-stained specimens were studied. The species possessed the characteristic tail of Tontoniidae, somatic ciliature classifying it as a Pseudotontonia, and cell proportions and oral ciliature corresponding to P. cornuta. Observation of live cells, however, revealed distinctive features as chloroplast-containing tentacles emerging just below the apical membranelles and an S-shaped proximal rim of the left margin of the oral cavity. These characters are eye-catching in live specimens, but have passed unnoticed till now because all previous studies on P. cornuta have been made on fixed samples.