Meeting Abstract

P2.157  Thursday, Jan. 5  Swarming to Schooling Transitions in Antarctic Krill Aggregations KANAGAWA, M*; MURPHY, DW; WEBSTER, DR; KAWAGUCHI, S; KING, R; YEN, J; Georgia Institute of Technology; Georgia Institute of Technology; Georgia Institute of Technology; Australian Antarctic Division; Australian Antarctic Division; Georgia Institute of Technology

Collective animal behavior is a natural phenomenon in which up to thousands of animals self-organize into groups without an apparent external stimulus. Antarctic krill (Euphausia superba) aggregations display such behavior as they transition from random swimming in swarms to coordinated swimming in schools. These schools may range up to 100 meters deep and several kilometers in length. The factors that initiate this self organization and the process by which it occurs are unknown, although animal aggregation density is thought to play a role. We present an analysis of a swarming to schooling progression in Antarctic krill using three-dimensional animal positions derived from stereophotogrammetric videos acquired at the Australian Antarctic Division (AAD) in Hobart, Tasmania. Using a 45-minute time series, animal positions and headings (taken at 3-minute intervals) were interrogated for parameters such as speed, polarity, and average nearest neighbor distance. The analysis showed a sharp change in the group polarity over a short period of time as the animals moved from swarming to schooling behavior. Possible factors that initiate this change will be discussed.