Meeting Abstract

15.3  Sunday, Jan. 4  Locomotory Biomechanics of Antarctic Krill MURPHY, D. W.*; WEBSTER, D. R.; KAWAGUCHI, S.; KING, R.; YEN, J.; Georgia Institute of Technology; Georgia Institute of Technology; Australian Antarctic Division; Australian Antarctic Division; Georgia Institute of Technology dwmurphy@gatech.edu

Antarctic krill (Euphausia superba) are the keystone species of the Antarctic food web, yet little is known about the biomechanics of their behavior and, in particular, their locomotion. Although it has been noted that these animals swim via a metachronal wave moving along their pleopods from posterior to anterior, the kinematics of these swimming appendages have not been characterized. Determining the kinematics of krill in various swimming modes will shed light on the fluid mechanics of krill locomotion and thereby deepen our understanding of krill sensing and schooling. High speed footage (250 fps) of freely swimming juvenile and adult Antarctic krill was acquired at the Australian Antarctic Division in Hobart, Tasmania. Various swimming modes were identified and two-dimensional kinematic parameters such as pleopod stroke frequency, amplitude, and tail position were examined as a function of these swimming modes. The effect of body length on the stroke frequency of hovering krill was also investigated by comparing the kinematics of adult and juvenile animals, and it was found that the stroke frequency decreased linearly from 6 Hz for a juvenile krill (11 mm body length) to 3 Hz for adult krill (45 mm body length). For comparision, Pacific krill (Euphausia pacifica), which live in warmer seawater with lower kinematic viscosity, have been shown to exhibit a higher stroke frequency of 9.5 Hz (~20 mm body length). The swimming kinematics data will be used to address hypotheses regarding low Reynolds number locomotion of krill.