The Ecological Conditions That Favor Tool Use and Innovation in Wild Bottlenose Dolphins (Tursiops sp.)

Dolphins are well known for their exquisite echolocation abilities, which enable them to detect and discriminate prey species and even locate buried prey. While these skills are widely used during foraging, some dolphins use tools to locate and extract prey. In the only known case of tool use in free-ranging cetaceans, a subset of bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia habitually employs marine basket sponge tools to locate and ferret prey from the seafloor. While it is clear that sponges protect dolphins' rostra while searching for prey, it is still not known why dolphins probe the substrate at all instead of merely echolocating for buried prey as documented at other sites. By ‘sponge foraging’ ourselves, we show that these dolphins target prey that both lack swimbladders and burrow in a rubble-littered substrate. Delphinid echolocation and vision are critical for hunting but less effective on such prey. Consequently, if dolphins are to access this burrowing, swimbladderless prey, they must probe the seafloor and in turn benefit from using protective sponges. We suggest that these tools have allowed sponge foraging dolphins to exploit an empty niche inaccessible to their non-tool-using counterparts. Our study identifies the underlying ecological basis of dolphin tool use and strengthens our understanding of the conditions that favor tool use and innovation in the wild

Stay-at-home circumstances do not produce sleep disorders: An international survey during the COVID-19 pandemic

Objective: The anxiety-related insomnia and other sleep disorders were mentioned as possible side effects of quarantine and stay-at-home conditions. The questions to be explored were: Are there discernable differences in hours of sleep and sleep habits between the normal operational environment and the stay-at-home condition? and How seriously anxiety-induced insomnia or other sleep disorders may affect individuals during the stay-at-home? Methods: This international prospective study analyzed results from the sleep-wake patterns questionnaire, daily logs, and interviews. During COVID-19 pandemic, surveys were administered to the healthy volunteers with stay-at-home for 14 days or more, without previous sleep disorders; volunteers were not involved in online education/work daily timetable-related activities. Results: We analyzed 14,000 subjects from 11 countries with average stay-at-home of 62 days. The most significant changes in sleep occurred during the first 14 days of stay-at-home. The difference in the sleep duration between weekdays and weekends disappeared. Most of the participants discontinued using alarm clocks. The total sleep time increased in duration up to 9:10 ± 1:16 to the end of the quarantine/stay-at-home (+1:34, p = 0.02). The age-dependent changes in napping habits occurred. Only 1.8% of participants indicated insomnia during the first 14-day period with a decline to 0.5% after two months of stay-at-home. Conclusion: During the stay-at-home situation, both duration and timing of sleep significantly differ from those of daily routine and most humans sleep longer than in a schedule-dependent operational environment. An appearance of anxiety-induced insomnia is extremely rare if a healthy individual is already in the stay-at-home situation. © 2020 Elsevier Inc