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Visual display is a crucial aspect of courtship, and their success relies on both display quality and the surrounding environment, such as the visual background. Cephalopods may release ink when attacked by predators or during aggressive interactions with conspecifics. Here, we report that ink is used as a part of the courtship display by males of the cuttlefish species Sepia andreana . Males of this species engage in a highly ritualized multimodal courtship using a pair of markedly long sexually dimorphic arms. At the climax of the courtship, the male releases a diffuse backdrop of ink near himself and then performs the specific courtship display by extending his sexually dimorphic arms and altering his body pattern to pale in front of this ink backdrop, and then proceeds to mate. This novel use of cephalopod ink could make the surroundings darker and more homogeneous, potentially serving as a temporary modification of the visual environment for courtship display., Competing Interests: The authors declare no conflicts of interest associated with this manuscript., (© 2024 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

In Japan, approximately 12,000,000 cellular phones with a videophone function have been distributed and are becoming an important part of the telemedicine infrastructure. By eye movement analysis, we investigated the effectiveness of eye contact using cellular videophones during medical interviews. Three male volunteers acted as first-time patients and were filmed using a high-resolution camera. The video of each of these volunteers was converted into pictures of three different sizes-70 cm x 40 cm (large picture), 26 cm x 20 cm (medium picture), and 14 cm x 12 cm (small picture)-and viewed on a 32-inch video monitor. The large, medium, and small pictures were considered to represent an actual medical interview, an interview via a television conference system, and an interview via a cellular videophone, respectively. Nine doctors watched these pictures, and their eye movements were recorded with a gaze-point recorder. After watching the videos, the doctors evaluated quality of three size pictures. Standard deviation values of the gaze point coordinates decreased with the picture size. However, a very low decrease was observed in the time ratio, during which the gaze point was on the face (eye contact rate); the rate was 92.2% (large picture), 91.8% (medium picture), and 85.1% (small picture). No statistical difference was observed between the values of the medium and small pictures. Subjective evaluations yielded low scores in the small pictures. The relatively high rate of eye contact rate in the small pictures suggests that a cellular videophone will be a good tool for telemedicine, although the usage by which the subjective evaluations can be improved should be determined by doctors.