Use of Social Information About Novel Food by Juvenile Solitary Forktongue Goby, Chaenogobius annularis

Abstract

Animals use various forms of information to reduce uncertainty about the environment and make adaptive decisions. They can acquire information directly from the environment (personal information) or by observing other individuals' behavior (social information). Since young animals in particular may benefit from acquiring social information owing to their lack of experience at this stage, social information in juveniles would be important even in solitary species. This possibility has, however, been less studied in juvenile solitary fishes. We examined whether juveniles of the solitary forktongue goby, Chaenogobius annularis, use social information about novel artificial food (fish-food flakes) and a novel food location (water surface). We first tested whether feeding on the novel food is facilitated by past experience to confirm that C. annularis juveniles could learn this information: compared with naïve juveniles, juveniles that previously experienced the novel food showed significantly shorter latencies to begin feeding (at the surface or underwater, hereafter first feeding), and to feed on the water's surface (hereafter, surface feeding). We then compared feeding on novel food between naïve juveniles paired with an experienced juvenile and those paired with a naïve juvenile. Naïve juveniles paired with an experienced juvenile fed significantly more frequently and sooner in both first and surface feedings than the randomly chosen naïve juveniles in each naïve pair. These results suggest that C. annularis juveniles use social information to learn about food and that social information use by juveniles is widespread among vertebrates, regardless of their sociality.