Hunting of the Reef Needlefish Strongylura incisa (Belonidae) for Small Schooling Pelagic Fishes on Shallow Lagoonal Reefs of Innafushi Mini-Atoll (Indian Ocean, Maldives, Ari Atoll)

Abstract

The tactics of the reef needlefish Strongylura incisa while hunting for small schooling pelagic fishes is described and photographically documented for the first time. Small flocks of reef needlefish enter the lagoon of the mini-atoll through passages in the reef at the beginning of the tide to hunt small schooling pelagic fishes, which move over the reef into the lagoon of the mini-atoll. In the lagoon, needlefish spread, and part of the flock (only a few) enter the reef itself, while the main part of the flock continues to move along the edge of the lagoonal reef in the direction of schools of small pelagic fishes moving through the reef and cuts the schools into supra-reef and lagoonal parts. Then the reef needlefish move onto the reef and begin to solitary hunt prey at a depth of only 10–15 cm. At such an insignificant depth a school of small pelagic fish loses the ability to turn synchronously. When attacking by a reef needlefish, members of the former school make individual chaotic movements and thereby become easier prey for the needlefish. However, hunting in shallow reef waters poses risks of collision with coral branches on the bottom for the reef needlefish.