2.3. Experimental protocol
2.3.1. Experiment 1: tentacle locomotion
To record and compare the fine-scale mechanistic feeding behavior of A. japonicus of different sizes, tentacle locomotion during feeding was observed using an upward-looking digital camera (Canon IXUS 125HS) located below the glass aquarium (60 cm × 60 cm × 50 cm) as described by Hudson et al. [6]. Six individuals of each size were observed. A pinch of sediment particles, insufficient to obstruct the view of camera, were provided to encourage feeding activity. The number of tentacles involved in feeding at any one time and the rates of tentacle insertion were analyzed frame-by-frame based on 100 separate tentacle movements.