1 Marine Biology, Department of Biology, Faculty of Science, Københavns Universitet2 IAMC-CNR, Istituto per l'Ambiente Marino Costiero3 Leibniz Institute of Freshwater Ecology and Inland Fisheries4 Uppsala Universitet5 Lübeck University of Applied Sciences6 Humboldt Universität zu Berlin7 Université Pierre et Marie Curie8 Marine Biology, Department of Biology, Faculty of Science, Københavns Universitet
The istiophorid family of billfishes is characterized by an extended rostrum or ‘bill’. While various functions (e.g. foraging and hydrodynamic benefits) have been proposed for this structure, until now no study has directly investigated the mechanisms by which billfishes use their rostrum to feed on prey. Here, we present the first unequivocal evidence of how the bill is used by Atlantic sailfish (Istiophorus albicans) to attack schooling sardines in the open ocean. Using high-speed video-analysis, we show that (i) sailfish manage to insert their bill into sardine schools without eliciting an evasive response and (ii) subsequently use their bill to either tap on individual prey targets or to slash through the school with powerful lateral motions characterized by one of the highest accelerations ever recorded in an aquatic vertebrate. Our results demonstrate that the combination of stealth and rapid motion make the sailfish bill an extremely effective feeding adaptation for capturing schooling prey.
Royal Society of London. Proceedings B. Biological Sciences, 2014, Vol 281, Issue 1784